Metal oxide-containing film-forming composition, metal oxide-containing film, metal oxide-containing film-bearing substrate, and patterning method

ABSTRACT

A metal oxide-containing film is formed from a heat curable composition comprising (A) a metal oxide-containing compound obtained through hydrolytic condensation between a hydrolyzable silicon compound and a hydrolyzable metal compound, (B) a hydroxide or organic acid salt of Li, Na, K, Rb or Cs, or a sulfonium, iodonium or ammonium compound, (C) an organic acid, and (D) an organic solvent. The metal oxide-containing film ensures effective pattern formation.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2007-303130 filed in Japan on Nov. 22, 2007,the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to a metal oxide-containing film-formingcomposition suitable for forming a metal oxide-containing film for useas an intermediate layer in a multilayer resist process which is used inmicropatterning in the manufacturing process of semiconductor devicesand the like, especially for forming such a metal oxide-containing filmby spin coating; a metal oxide-containing film formed therefrom; a metaloxide-containing film-bearing substrate; and a patterning method usingthe same.

BACKGROUND ART

In the drive for higher integration and operating speeds in LSI devices,the pattern feature size is made drastically finer. Under theminiaturizing trend, the lithography has achieved formation of finerpatterns by using a light source with a shorter wavelength and by achoice of a proper resist composition for the shorter wavelength.Predominant among others are positive photoresist compositions which areused as a single layer. These single-layer positive photoresistcompositions are based on resins possessing a framework havingresistance to dry etching with chlorine or fluorine gas plasma andprovided with a resist mechanism that exposed areas become dissolvable.Typically, the resist composition is coated on a substrate to beprocessed (referred to as “processable substrate,” hereinafter) andexposed to a pattern of light, after which the exposed areas of theresist coating are dissolved to form a pattern. Then, the substrate canbe processed by dry etching with the remaining resist pattern serving asan etching mask.

In an attempt to achieve a finer feature size, i.e., to reduce thepattern width with the thickness of a photoresist coating keptunchanged, the photoresist coating becomes low in resolutionperformance. If the photoresist coating is developed with a liquiddeveloper to form a pattern, the so-called “aspect ratio” (depth/width)of the resist pattern becomes too high, resulting in pattern collapse.For this reason, the miniaturization is accompanied by a thicknessreduction of the photoresist coating (thinner coating).

On the other hand, a method commonly used for the processing of aprocessable substrate is by processing a substrate by dry etching withthe patterned photoresist film made an etching mask. Since a dry etchingmethod capable of establishing a full etching selectivity between thephotoresist film and the processable substrate is not available inpractice, the resist film is also damaged during substrate processing.That is, the resist film breaks down during substrate processing,failing to transfer the resist pattern to the processable substratefaithfully. As the pattern feature size is reduced, resist materials arerequired to have higher resistance to dry etching.

With the progress of the exposure wavelength toward a shorterwavelength, the resin in resist compositions is required to have lesslight absorption at the exposure wavelength. In response to changes fromi-line to KrF and to ArF, the resin has made a transition to novolacresins, polyhydroxystyrene and aliphatic polycyclic skeleton resins.Actually, the etching rate under the above-indicated dry etchingconditions has been accelerated. Advanced photoresist compositionsfeaturing a high resolution tend to be rather low in etching resistance.This suggests the inevitableness that a processable substrate is dryetched through a thinner photoresist coating having weaker etchingresistance. It is urgently required to have the material and processsuited in this processing stage.

One solution to these problems is a multilayer resist process. Theprocess involves forming an intermediate film on a processablesubstrate, forming a photoresist film (resist overcoat film) thereon,wherein the intermediate film with different etching selectivity fromthe resist overcoat film intervenes between the resist overcoat film andthe processable substrate, patterning the resist overcoat film, dryetching the intermediate film through the overcoat resist pattern as anetching mask for thereby transferring the pattern to the intermediatefilm, and dry etching the processable substrate through the intermediatefilm pattern as an etching mask for thereby transferring the pattern tothe processable substrate.

Included in the multilayer resist process is a bi-layer resist process.One exemplary bilayer resist process uses a silicon-containing resin asthe overcoat resist material and a novolac resin as the intermediatefilm (e.g., JP-A 6-95385). The silicon resin exhibits good resistance toreactive dry etching with an oxygen plasma, but is readily etched awaywith a fluorine gas plasma. On the other hand, the novolac resin isreadily etched away by reactive dry etching with an oxygen gas plasma,but exhibits good resistance to dry etching with fluorine and chlorinegas plasmas. Thus, a novolac resin film is formed on a processablesubstrate as a resist intermediate film, and a silicon-containing resinis coated thereon as a resist overcoat film. Subsequently, thesilicon-containing resist film is patterned by exposure to energyradiation and post-treatments including development. While the patternedsilicon-containing resist film serves as an etching mask, reactive dryetching with an oxygen plasma is carried out for etching away a portionof the novolac resin where the resist pattern has been removed, therebytransferring the pattern to the novolac film. While the patterntransferred to the novolac film serves as an etching mask, theprocessable substrate is etched with a fluorine or chlorine gas plasmafor transferring the pattern to the processable substrate.

In the pattern transfer by dry etching, a transfer pattern having arelatively good profile is obtained if the etching mask has asatisfactory etching resistance. Since problems like pattern collapsecaused by such factors as friction by a developer during resistdevelopment are unlikely to occur, a pattern having a relatively highaspect ratio is produced. Therefore, even though a fine pattern couldnot be formed directly from a resist film of novolac resin having athickness corresponding to the thickness of an intermediate film becauseof pattern collapse during development due to the aspect ratio problem,the use of the bi-layer resist process enables to produce a fine patternof novolac resin having a sufficient thickness to serve as a mask fordry etching of the processable substrate.

Also included in the multilayer resist process is a tri-layer resistprocess which can use general resist compositions as used in thesingle-layer resist process. In the tri-layer resist process, forexample, an organic film of novolac resin or the like is formed on aprocessable substrate as a resist undercoat film, a silicon-containingfilm is formed thereon as a resist intermediate film, and an ordinaryorganic photoresist film is formed thereon as a resist overcoat film. Ondry etching with a fluorine gas plasma, the resist overcoat film oforganic nature provides a satisfactory etching selectivity ratiorelative to the silicon-containing resist intermediate film. Then, theresist pattern is transferred to the silicon-containing resistintermediate film by dry etching with a fluorine gas plasma. With thisprocess, even on use of a resist composition which is difficult to forma pattern having a sufficient thickness to allow for direct processingof a processable substrate, or a resist composition which hasinsufficient dry etching resistance to allow for substrate processing, apattern of novolac film having sufficient dry etching resistance toallow for substrate processing is obtainable like the bilayer resistprocess, as long as the pattern can be transferred to thesilicon-containing film.

The silicon-containing resist intermediate films used in the tri-layerresist process described above include silicon-containing inorganicfilms deposited by CVD, such as SiO₂ films (e.g., JP-A 7-183194) andSiON films (e.g., JP-A 7-181688); and films formed by spin coating, suchas spin-on-glass (SOG) films (e.g., JP-A 5-291208, J. Appl. Polym. Sci.,Vol. 88, 636-640 (2003)) and crosslinkable silsesqutoxane films (e.g.,JP-A 2005-520354). Polysilane films (e.g., JP-A 11-60735) would also beuseful. Of these, the SiO₂ and SiON films have a good function as a dryetching mask during dry etching of an underlying organic film, butrequire a special equipment for their deposition. By contrast, the SOGfilms, crosslinkable silsesquioxane films and polysilane films arebelieved high in process efficiency because they can be formed simply byspin coating and heating.

The applicable range of the multilayer resist process is not restrictedto the attempt of increasing the maximum resolution of resist film. Forexample, in a via-first method which is one of substrate processingmethods where an intermediate substrate to be processed has large steps,an attempt to form a pattern with a single resist film encountersproblems like inaccurate focusing during resist exposure because of asubstantial difference in resist film thickness. In such a case, stepsare buried by a sacrificial film for planarization, after which a resistfilm is formed thereon and patterned. This situation entails inevitableuse of the multilayer resist process mentioned above (e.g., JP-A2004-349572).

While silicon-containing films are conventionally used in the multilayerresist process, they suffer from several problems. For example, as iswell known in the art, where an attempt is made to form a resist patternby photolithography, exposure light is reflected by the substrate andinterferes with the incident light, incurring the problem of so-calledstanding waves. To produce a microscopic pattern of a resist filmwithout edge roughness, an antireflective coating (ARC) must be providedas an intermediate layer. Reflection control is essential particularlyunder high-NA exposure conditions of the advanced lithography.

In the multilayer resist process, especially the process of forming asilicon-containing film as an intermediate layer by CVD, it becomesnecessary for reflection control purposes to provide an organicantireflective coating between the resist overcoat film and thesilicon-containing intermediate film. However, the provision of theorganic ARC entails the necessity that the organic ARC be patterned withthe resist overcoat film made a dry etching mask. That is, the organicARC is dry etched with the resist overcoat film made a dry etching mask,after which the process proceeds to processing of the silicon-containingintermediate layer. Then the overcoat photoresist must bear anadditional load of dry etching corresponding to the processing of theARC. While photoresist films used in the advanced lithography becomethinner, this dry etching load is not negligible. Therefore, greaterattention is paid to the tri-layer resist process in which alight-absorbing silicon-containing film not creating such an etchingload is applied as an intermediate film.

Known light-absorbing silicon-containing intermediate films includelight-absorbing silicon-containing films of spin coating type. Forexample, JP-A 2005-15779 discloses the provision of an aromaticstructure as the light-absorbing structure. Since the aromatic ringstructure capable of effective light absorption acts to reduce the rateof dry etching with a fluorine gas plasma, this approach isdisadvantageous for the purpose of dry etching the intermediate filmwithout an additional load to the photoresist film. Since it is thusundesirable to incorporate a large amount of such light-absorbingsubstituent groups, the amount of incorporation must be limited to theminimum.

Further, the dry etching rate of the resist undercoat film duringreactive dry etching with an oxygen gas plasma as commonly used in theprocessing of the resist undercoat film with the intermediate film madea dry etching mask is preferably low so as to increase the etchingselectivity ratio between the intermediate film and the undercoat film.To this end, the intermediate film is desired to have a higher contentof silicon which is highly reactive with fluorine etchant gas. Therequirement arising from the conditions of processing both the overcoator photoresist film and the undercoat or organic film gives preferenceto an intermediate film having a higher content of silicon which ishighly reactive with fluorine gas.

In actual silicon-containing intermediate film-forming compositions ofspin coating type, however, organic substituent groups are incorporatedinto the silicon-containing compounds so that the silicon-containingcompounds may be dissolvable in organic solvents. Of thesilicon-containing intermediate films known in the art, an SOGfilm-forming composition adapted for KrF excimer laser lithography isdisclosed in J. Appl. Polym. Sci., Vol. 88, 636-640 (2003). However,since light-absorbing groups are described nowhere, it is believed thatthis composition forms a silicon-containing film without anantireflective function. This film fails to hold down reflection duringexposure by the lithography using the advanced high-NA exposure system.It would be impossible to produce microscopic pattern features.

In the advanced semiconductor process using such a high-NA exposuresystem, the photoresist film has seen a more outstanding reduction inthickness. Then in etching the silicon-containing intermediate filmusing a thin photoresist film as an etching mask, an attempt to increasethe silicon content of the silicon-containing intermediate film whilepossessing an antireflection function, as such, is expected difficult tofacilitate pattern transfer to the intermediate film. There is a demandfor an intermediate film material having a higher etching rate.

In addition to the dry etching properties and antireflection effect, thecomposition for forming an intermediate film with a high silicon contentsuffers from several problems, of which shelf stability is mostoutstanding. The shelf stability relates to the phenomenon that acomposition comprising a silicon-containing compound changes itsmolecular weight during shelf storage as a result of condensation ofsilanol groups on the silicon-containing compound. Such molecular weightchanges show up as film thickness variations and lithography performancevariations. In particular, the lithography performance is sensitive, andso, even when the condensation of silanol groups within the moleculetakes place merely to such an extent that it does not show up as a filmthickness buildup or molecular weight change, it can be observed asvariations of microscopic pattern features.

As is known in the art, such highly reactive silanol groups can berendered relatively stable if they are kept in acidic conditions. See C.J. Brinker and G. W. Scherer, “Sol-Gel Science: The Physics andChemistry of Sol-Gel Processing,” Academic Press, San Diego (1990).Further, addition of water improves the shelf stability as disclosed inJ. Appl. Polym. Sci., Vol. 88, 636-640 (2003), JP-A 2004-157469 and JP-A2004-191386. However, the silicon-containing compounds prepared by themethods of these patent publications are not inhibited completely fromcondensation reaction of silanol groups even when any of these means istaken. The silicon-containing compound in the composition slowly alterswith the passage of time, and a silicon-containing film formed from suchan altered composition changes in nature. Then the composition must beheld in a refrigerated or frozen state just until use, and on use, bebrought back to the service temperature (typically 23° C.) and beconsumed quickly.

DISCLOSURE OF THE INVENTION

The present invention relates to a process involving the steps ofdisposing a metal oxide-containing film on an organic film, disposing aphotoresist film thereon, and forming a resist pattern. An object of thepresent invention is to provide a metal oxide-containing film-formingcomposition in which (1) the metal oxide-containing film has alight-absorbing capability to allow for pattern formation even underhigh-NA exposure conditions, (2) the metal oxide-containing film servesas a satisfactory dry etching mask between the overlying layer orphotoresist film and the underlying layer or organic film, and (3) thecomposition is fully shelf stable. Another object is to provide a metaloxide-containing film formed from the composition, a substrate havingthe metal oxide-containing film disposed thereon, and a patterningmethod.

Making investigations on the lithographic properties and stability of ametal oxide-containing intermediate film-forming composition, theinventors have found that a composition is obtained by combining (A) ametal oxide-containing compound obtained through hydrolytic condensationbetween a hydrolyzable silicon compound and a hydrolyzable metalcompound with components (B), (C), and (D) defined below; and that (1) ametal oxide-containing film formed from the composition holds downreflection under high-NA exposure conditions of either dry or immersionlithography technique when light-absorbing groups are incorporated inthe metal oxide-containing compounds, (2) the metal oxide-containingfilm has a sufficient etching selectivity ratio to serve as a dryetching mask, and (3) the composition is fully shelf stable so that itslithography performance undergoes little or no change over time.

In a first aspect, the invention provides a heat curable metaloxide-containing film-forming composition comprising

(A) a metal oxide-containing compound obtained through hydrolyticcondensation between one or multiple hydrolyzable silicon compoundshaving the general formula (1) and one or multiple hydrolyzable metalcompounds having the general formula (2):

R¹ _(m1)R² _(m2)R³ _(m3)Si(OR)_((4-m1-m2-m3))   (1)

wherein R is an alkyl of 1 to 6 carbon atoms, R¹, R² and R³ each arehydrogen or a monovalent organic group of 1 to 30 carbon atoms, m1, m2and m3 each are 0 or 1, and m1+m2+m3 is an integer of 0 to 3,

U(OR⁴)_(m4)(OR⁵)_(m5)   (2)

wherein U is an element selected from Group III, IV and V elements inthe Periodic Table, excluding silicon, R⁴ and R⁵ each are an organicgroup of 1 to 30 carbon atoms, m4 and m5 each are an integer inclusiveof 0, and m4+m5 is equal to the valence of U,

(B) at least one compound having the general formula (3) or (4):

L_(a)H_(b)X   (3)

wherein L is lithium, sodium, potassium, rubidium or cesium, X is ahydroxyl group or a mono or polyfunctional organic acid residue of 1 to30 carbon atoms, “a” is an integer of at least 1, “b” is 0 or an integerof at least 1, and a+b is equal to the valence of hydroxyl group ororganic acid residue,

M_(a)H_(b)A   (4)

wherein M is sulfonium, iodonium or ammonium, A is X or anon-nucleophilic counter ion, “a” and “b” are as defined above, and a+bis equal to the valence of hydroxyl group, organic acid residue ornon-nucleophilic counter ion,

(C) a mono or polyfunctional organic acid of 1 to 30 carbon atoms, and

(D) an organic solvent.

In general, when a hydrolyzable silicon compound and a hydrolyzablemetal compound (both being often referred to as “monomers”) arecontacted with water in the presence of a hydrolytic condensationcatalyst, hydrolyzable substituent groups on the monomers undergohydrolysis to form terminal reactive groups. The terminal reactivegroups, in turn, undergo condensation reaction with other terminalreactive groups or unreacted hydrolyzable groups, to form —SiOSi—,—SiOU— or —UOU— bonds. This reaction occurs repeatedly andconsecutively, forming a metal oxide-containing compound which isreferred to as an oligomer or polymer or sometimes sol. At this point,among terminal reactive groups produced by hydrolytic reaction in thesystem and available from the monomers, oligomer or polymer,condensation reaction takes place from the highest reactivity groupsconsecutively to lower reactivity groups, whereupon terminal reactivegroups belonging to the monomers, oligomer and polymer are consumed, anda metal oxide-containing compound forms instead. This condensationreaction proceeds infinitely and sometimes until the metaloxide-containing compound solution has eventually gelled. Often, silanolgroups having relatively low reactivity are finally left as the terminalreactive groups.

However, the condensation reaction of terminal silanol groups issometimes restrained at a specific pH, as reported in C. J. Brinker andG. W. Scherer, “Sol-Gel Science: The Physics and Chemistry of Sol-GelProcessing,” Academic Press, San Diego (1990). It is described in J.Appl. Polym. Sci., Vol. 88, 636-640 (2003) that the reaction system isstabilized around pH 1.5, which pH is referred to as “stable pH,”hereinafter.

It has been found that the composition is improved in shelf stabilitywhen it is controlled at a stable pH with component (C).

Prior art metal oxide-containing compounds are cured at elevatedtemperatures above 300° C. or with the aid of an acid catalyst derivedfrom a thermal acid generator. According to the invention, when thecomposition is coated and heat cured, component (B) included thereinacts to alter the pH in proximity to terminal silanol groups from thestable pH region to an unstable pH region (approximately pH 3, see C. J.Brinker and G. W. Scherer, “Sol-Gel Science: The Physics and Chemistryof Sol-Gel Processing,” Academic Press, San Diego (1990)), so that themetal oxide-containing film can be effectively cured. If heat curedunder the same conditions as the prior art temperature conditions, thecomposition forms a film having an advanced degree of crosslinking ascompared with the prior art cured films. The migration of effectiveingredients in the resist film to the metal oxide-containing film isthus prevented, and lithographic properties equivalent to ordinaryorganic ARC are available.

A technical combination of pH control, stabilizer and crosslinkingcatalyst in the above-mentioned way provides a composition which remainsstable at room temperature and becomes effectively curable at elevatedtemperature. The composition can form a metal oxide-containingantireflective coating which has stability equivalent to conventionalorganic ARCs.

In a preferred embodiment, the composition may further comprise (E) asilicon-containing compound obtained through hydrolytic condensation ofone or multiple hydrolyzable silicon compounds having the generalformula (5):

R⁶ _(m6)R⁷ _(m7)R⁸ _(m8)Si(OR⁹)_((4-m6-m7-m8))   (5)

wherein R⁹ is an alkyl of 1 to 6 carbon atoms, R⁶, R⁷ and R⁸ each arehydrogen or a monovalent organic group of 1 to 30 carbon atoms, m6, m7and m8 each are 0 or 1, and m6+m7+m8 is an integer of 0 to 3.

The inclusion of a silicon-containing compound obtained throughhydrolytic condensation of a silicon-containing monomer suggests apossible combination of properties of the metal oxide-containingcompound with properties of the silicon-containing compound. There isobtained a metal oxide-containing ARC-forming composition havingsurpassing properties over the prior art organic ARCS.

In a preferred embodiment, the metal oxide-containing compound (A) isobtained through hydrolytic condensation between the compounds havingthe general formulae (1) and (2) in the presence of an acid catalyst.Use of an acid as the catalyst for hydrolytic condensation of monomersleads to a metal oxide-containing ARC-forming composition which is shelfstable and has lithographic properties equivalent to those ofconventional organic ARCs.

Typically the acid catalyst comprises at least one compound selectedfrom mineral acids and sulfonic acid derivatives. Use of a mineral acidor sulfonic acid derivative as the catalyst for hydrolytic condensationof monomers leads to a metal oxide-containing ARC-forming compositionwhich is shelf stable and has lithographic properties equivalent tothose of conventional organic ARCs.

In a preferred embodiment, the metal oxide-containing compound (A)comprises a metal oxide-containing compound obtained by effectinghydrolytic condensation between the compounds having formulae (1) and(2) in the presence of an acid catalyst to form a reaction mixturecontaining the metal oxide-containing compound, and substantiallyremoving the acid catalyst from the reaction mixture.

The metal oxide-containing compounds prepared in the prior art are usedin coating film-forming compositions without substantially removing theacid catalysts used in hydrolytic condensation. Due to the carry-over ofthe condensation reaction catalysts, the compositions fail to restraincondensation of silanol even when they are controlled at a stable pH.The resultant compositions are shelf unstable.

It has been found that an outstanding improvement in shelf stability isachieved when a metal oxide-containing compound is obtained by effectinghydrolytic condensation in the presence of an optimum acid catalyst andsubstantially removing the acid catalyst from the reaction mixture, andcomponent (C) is combined therewith.

In a preferred embodiment, U in formula (2) is selected from amongboron, aluminum, gallium, yttrium, germanium, titanium, zirconium,hafnium, bismuth, tin, phosphorus, vanadium, arsenic, antimony, niobium,and tantalum. A metal oxide-containing film comprising a metalrepresented by U has a high etching rate, as compared with asilicon-containing film free of such a metal. That is, an intermediatefilm capable of pattern transfer even when a photoresist film having areduced thickness is used as the etching mask can be formed.

In a preferred embodiment, the compound of formula (1) is used in agreater molar amount than the compound of formula (2) during hydrolyticcondensation, that is, (1)>(2). The presence of more silicon than themetal represented by U in the intermediate layer provides a sufficientetching selectivity when the underlying layer is etched using theintermediate layer as an etching mask. That is, an intermediate filmcapable of pattern transfer to the underlying layer can be formed.

In a preferred embodiment, M in formula (4) is tertiary sulfonium,secondary iodonium, or quaternary ammonium. When a compositioncomprising a compound of formula (4) as component (B) is used, a filmhaving an advanced degree of crosslinking can be formed followingcuring. This prevents migration of effective ingredients in the resistfilm to the metal oxide-containing film, and achieves lithographicproperties equivalent to conventional organic ARCs.

In a preferred embodiment, M in formula (4) is photo-degradable. Ifcomponent (B) does not completely volatilize off during heat curing,part of component (B) can be left in the metal oxide-containing film.This component can adversely affect the profile of resist pattern. Ifcomponent (B) used is such a compound that the cation moiety is degradedduring exposure, it becomes possible to prevent the profile of resistpattern from being adversely affected during exposure. While the cureability of the metal oxide-containing compound is drastically improved,a metal oxide-containing cured film having a good lithographic profilecan be provided.

The preferred metal oxide-containing film-forming composition mayfurther comprise water. When water is added to the composition, terminalsilanol groups in the metal oxide-containing compounds are activated sothat a denser film results from heat curing reaction. Such a dense filmallows the overlying photoresist layer to exert lithographic performanceequivalent to conventional organic ARCs.

The metal oxide-containing film-forming composition may further comprisea photoacid generator. If component (B) does not completely volatilizeoff during heat curing and/or exposure, part of component (B) can beleft in the metal oxide-containing film, which can adversely affect theprofile of resist pattern. If an acid is generated in the metaloxide-containing film during resist pattern formation, it prevents theprofile of resist pattern from being adversely affected.

In a preferred embodiment, the composition may further comprise a monoor polyhydric alcohol substituted with a cyclic ether. Making furtherinvestigations on the metal oxide-containing compound to inhibitcondensation between terminal silanol groups therein near roomtemperature, the inventors have found that a mono or polyhydric alcoholsubstituted with a cyclic ether is effective as a stabilizer forinhibiting condensation near room temperature whereby the composition isoutstandingly improved in shelf stability.

In a second aspect, the invention provides a metal oxide-containing filmfor use in a multilayer resist process involving the steps of forming anorganic film on a processable substrate, forming a metaloxide-containing film thereon, further forming a resist film thereonfrom a silicon-free chemically amplified resist composition, patterningthe resist film, patterning the metal oxide-containing film using theresist film pattern, patterning the underlying organic film with themetal oxide-containing film pattern serving as an etching mask, andetching the processable substrate with the patterned organic filmserving as an etching mask, the metal oxide-containing film being formedfrom the composition defined above.

Preferably, the metal oxide-containing film formed from the compositionis used in the multilayer resist process wherein the process furtherinvolves the step of disposing an organic antireflective coating betweenthe resist film and the metal oxide-containing film.

In a third aspect, the invention provides a substrate having formedthereon, in sequence, an organic film, a metal oxide-containing film ofthe composition defined above, and a photoresist film. Preferably, thesubstrate further has an organic antireflective coating between themetal oxide-containing film and the photoresist film. Preferably, theorganic film is a film having an aromatic framework.

In a fourth aspect, the invention provides a method for forming apattern in a substrate, comprising the steps of providing the substrateof the third aspect, exposing a pattern circuit region of thephotoresist film to radiation, developing the photoresist film with adeveloper to form a resist pattern, dry etching the metaloxide-containing film with the resist pattern made an etching mask,etching the organic film with the patterned metal oxide-containing filmmade an etching mask, and etching the substrate with the patternedorganic film made an etching mask, for forming a pattern in thesubstrate.

In a fifth aspect, the invention provides a method for forming a patternin a substrate, comprising the steps of providing the substrate of thethird aspect further having an organic antireflective coating, exposinga pattern circuit region of the photoresist film to radiation,developing the photoresist film with a developer to form a resistpattern, dry etching the antireflective coating and the metaloxide-containing film with the resist pattern made an etching mask,etching the organic film with the patterned metal oxide-containing filmmade an etching mask, and etching the substrate with the patternedorganic film made an etching mask, for forming a pattern in thesubstrate.

Preferably, the organic film is a film having an aromatic framework.Typically, the exposing step is carried out by photolithography usingradiation having a wavelength equal to or less than 300 nm. When theintermediate film and the substrate are used and the substrate ispatterned by lithography, a microscopic pattern can be formed in thesubstrate at a high accuracy. When an organic film having an aromaticframework is used, it not only exerts an antireflection effect in thelithography step, but also has sufficient etching resistance in thesubstrate etching step, allowing for etch processing. Particularly whenpatterning is carried out by lithography using radiation with wavelengthequal to or less than 300 nm, especially ArF excimer laser radiation, amicroscopic pattern can be formed at a high accuracy.

BENEFITS OF THE INVENTION

The use of a metal oxide-containing intermediate film formed from theheat curable metal oxide-containing film-forming composition of theinvention allows the overlying photoresist film to be patternedeffectively. Since the metal oxide-containing intermediate film providesa high etching selectivity relative to an organic material, the formedphotoresist pattern can be transferred in sequence to the metaloxide-containing intermediate film and the organic undercoat film by adry etching process. While the advancement of the semiconductor processtoward finer feature size entails a thickness reduction of photoresistfilm which interferes with pattern transfer to a conventionalsilicon-containing intermediate film, the heat curable metaloxide-containing film-forming composition of the invention allows aphotoresist film with reduced thickness to be used as the etching mask,so that the photoresist pattern can be transferred to the substrate at ahigh accuracy. The composition is effective in minimizing the occurrenceof pattern defects after lithography and is shelf stable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the specification, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise.

The notation (Cn-Cm) means a group containing from n to m carbon atomsper group.

The terms “mono or polyfunctional” and “mono or polyhydric” are used ina similar meaning. For example, the “mono or polyfunctional” compound isa compound having a functionality of 1, 2 or more.

Component A

Component (A) in the heat curable metal oxide-containing film-formingcomposition of the invention is a metal oxide-containing compoundobtained through hydrolytic condensation of monomers, specifically ahydrolyzable silicon compound having the general formula (1) and ahydrolyzable metal compound having the general formula (2). Thepreferred method of preparing the metal oxide-containing compound isexemplified below, but not limited thereto.

One starting monomer is a hydrolyzable silicon compound having thegeneral formula (1):

R¹ _(m1)R² _(m2)R³ _(m3)Si(OR)_((4-m1-m2-m3))   (1)

wherein R is an alkyl group of 1 to 6 carbon atoms, especially 1 to 3carbon atoms, R¹, R² and R³ each are hydrogen or a monovalent organicgroup of 1 to 30 carbon atoms, m1, m2 and m3 each are equal to 0 or 1,and m1+m2+m3 is equal to an integer of 0 to 3, and preferably 0 or 1.

As used herein, the term “organic group” refers to a group containingcarbon, specifically carbon and hydrogen, and optionally nitrogen,oxygen, sulfur, silicon and other elements. The organic groupsrepresented by R¹, R² and R³ include unsubstituted monovalenthydrocarbon groups, such as straight, branched or cyclic alkyl, alkenyl,alkynyl, aryl and aralkyl groups, substituted forms of the foregoinghydrocarbon groups in which one or more hydrogen atoms are substitutedby epoxy, alkoxy, hydroxyl or the like, groups of the general formula(6), shown later, for example, groups which are separated by such amoiety as —O—, —CO—, —OCO—, —COO—, or —OCOO—, and organic groupscontaining a silicon-silicon bond.

Preferred examples of R¹, R² and R³ in the monomers of formula (1)include hydrogen, alkyl groups such as methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl,2-ethylbutyl, 3-ethylbutyl, 2,2-diethylpropyl, cyclopentyl, n-hexyl, andcyclohexyl, alkenyl groups such as vinyl and allyl, alkynyl groups suchas ethynyl, and light-absorbing groups like aryl groups such as phenyland tolyl, and aralkyl groups such as benzyl and phenethyl.

Examples of suitable tetraalkoxysilanes corresponding to formula (1)wherein m1=0, m2=0 and m3=0 include tetramethoxysilane,tetraethoxysilane, tetra-n-propoxysilane, and tetra-iso-propoxysilane.Of these, preferred are tetramethoxysilane and tetraethoxysilane.

Examples of suitable trialkoxysilanes corresponding to formula (1)wherein m1=1, m2=0 and m3=0 include trimethoxysilane, triethoxysilane,tri-n-propoxysilane, triisopropoxysilane, methyltrimethoxysilane,methyltriethoxysilane, methyltri-n-propoxysilane,methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane,ethyltri-n-propoxysilane, ethyltriisopropoxysilane,vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane,vinyltriisopropoxysilane, n-propyltrimethoxysilane,n-propyltriethoxysilane, n-propyltri-n-propoxysilane,n-propyltriisopropoxysilane, isopropyltrimethoxysilane,isopropyltriethoxysilane, isopropyltri-n-propoxysilane,isopropyltriisopropoxysilane, n-butyltrimethoxysilane,n-butyltriethoxysilane, n-butyltri-n-propoxysilane,n-butyltriisopropoxysilane, sec-butyltrimethoxysilane,sec-butyltriethoxysilane, sec-butyltri-n-propoxysilane,sec-butyltriisopropoxysilane, t-butyltrimethoxysilane,t-butyltriethoxysilane, t-butyltri-n-propoxysilane,t-butyltriisopropoxysilane,-cyclopropyltrimethoxysilane,cyclopropyltriethoxysilane, cyclopropyltri-n-propoxysilane,cyclopropyltriisopropoxysilane, cyclobutyltrimethoxysilane,cyclobutyltriethoxysilane, cyclobutyltri-n-propoxysilane,cyclobutyltriisopropoxysilane, cyclopentyltrimethoxysilane,cyclopentyltriethoxysilane, cyclopentyltri-n-propoxysilane,cyclopentyltriisopropoxysilane, cyclohexyltrimethoxysilane,cyclohexyltriethoxysilane, cyclohexyltri-n-propoxysilane,cyclohexyltriisopropoxysilane, cyclohexenyltrimethoxysilane,cyclohexenyltriethoxysilane, cyclohexenyltri-n-propoxysilane,cyclohexenyltriisopropoxysilane, cyclohexenylethyltrimethoxysilane,cyclohexenylethyltriethoxysilane, cyclohexenylethyltri-n-propoxysilane,cyclohexenylethyltriisopropoxysilane, cyclooctanyltrimethoxysilane,cyclooctanyltriethoxysilane, cyclooctanyltri-n-propoxysilane,cyclooctanyltriisopropoxysilane, cyclopentadienylpropyltrimethoxysilane,cyclopentadienylpropyltriethoxysilane,cyclopentadienylpropyltri-n-propoxysilane,cyclopentadienylpropyltriisopropoxysilane,bicycloheptenyltrimethoxysilane, bicycloheptenyltriethoxysilane,bicycloheptenyltri-n-propoxysilane, bicycloheptenyltriisopropoxysilane,bicycloheptyltrimethoxysilane, bicycloheptyltriethoxysilane,bicycloheptyltri-n-propoxysilane, bicycloheptyltriisopropoxysilane,adamantyltrimethoxysilane, adamantyltriethoxysilane,adamantyltri-n-propoxysilane, adamantyltriisopropoxysilane, etc.Suitable light-absorbing monomers include phenyltrimethoxysilane,phenyltriethoxysilane, phenyltri-n-propoxysilane,phenyltriesopropoxysilane, benzyltrimethoxysilane,benzyltriethoxysilane, benzyltri-n-propoxysilane,benzyltriisopropoxysilane, tolyltrimethoxysilane, tolyltriethoxysilane,tolyltri-n-propoxysilane, tolyltriisopropoxysilane,phenethyltrimethoxysilane, phenethyltriethoxysilane,phenethyltri-n-propoxysilane, phenethyltriisopropoxysilane,naphthyltrimethoxysilane, naphthyltriethoxysilane,naphthyltri-n-propoxysilane, naphthyltriisopropoxysilane, etc.

Of these, preferred are methyltrimethoxysilane, methyltriethoxysilane,ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane,isopropyltrimethoxysilane, isopropyltriethoxysilane,n-butyltrimethoxysilane, n-butyltriethoxysilane,isobutyltrimethoxysilane, isobutyltriethoxysilane,allyltrimethoxysilane, allyltriethoxysilane,cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane,cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane,cyclohexenyltrimethoxysilane, cyclohexenyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, benzyltrimethoxysilane,benzyltriethoxysilane, phenethyltrimethoxysilane, andphenethyltriethoxysilane.

Examples of suitable dialkoxysilanes corresponding to formula (1)wherein m1=1, m2=1 and m3=0 include dimethyldimethoxysilane,dimethyldiethoxysilane, methylethyldimethoxysilane,methylethyldiethoxysilane, dimethyldi-n-propoxysilane,dimethyldiisopropoxysilane, diethyldimethoxysilane,diethyldiethoxysilane, diethyldi-n-propoxysilane,diethyldiisopropoxysilane, di-n-propyldimethoxysilane,di-n-propyldiethoxysilane, di-n-propyl-di-n-propoxysilane,di-n-propyldiisopropoxysilane, diisopropyldimethoxysilane,diisopropyldiethoxysilane, diisopropyldi-n-propoxysilane,diisopropyldiisopropoxysilane, di-n-butyldimethoxysilane,di-n-butyldiethoxysilane, di-n-butyldi-n-propoxysilane,di-n-butyldiisopropoxysilane, di-sec-butyldimethoxysilane,di-sec-butyldiethoxysilane, di-sec-butyldi-n-propoxysilane,di-sec-butyldiisopropoxysilane, di-t-butyldimethoxysilane,di-t-butyldiethoxysilane, di-t-butyldi-n-propoxysilane,di-t-butyldiisopropoxysilane, dicyclopropyldimethoxysilane,dicyclopropyldiethoxysilane, dicyclopropyldi-n-propoxysilane,dicyclopropyldiisopropoxysilane, dicyclobutyldimethoxysilane,dicyclobutyldiethoxysilane, dicyclobutyldi-n-propoxysilane,dicyclobutyldiisopropoxysilane, dicyclopentyldimethoxysilane,dicyclopentyldiethoxysilane, dicyclopentyldi-n-propoxysilane,dicyclopentyldiisopropoxysilane, dicyclohexyldimethoxysilane,dicyclohexyldiethoxysilane, dicyclohexyldi-n-propoxysilane,dicyclohexyldiisopropoxysilane, dicyclohexenyldimethoxysilane,dicyclohexenyldiethoxysilane, dicyclohexenyldi-n-propoxysilane,dicyclohexenyldiisopropoxysilane, dicyclohexenylethyldimethoxysilane,dicyclohexenylethyldiethoxysilane,dicyclohexenylethyldi-n-propoxysilane,dicyclohexenylethyldiisopropoxysilane, dicyclooctanyldimethoxysilane,dicyclooctanyldiethoxysilane, dicyclooctanyldi-n-propoxysilane,dicyclooctanyldiisopropoxysilane,dicyclopentadienylpropyldimethoxysilane,dicyclopentadienylpropyldiethoxysilane,dicyclopentadienylpropyldi-n-propoxysilane,dicyclopentadienylpropyldiisopropoxysilane,bisbicycloheptenyldimethoxysilane, bisbicycloheptenyldiethoxysilane,bisbicycloheptenyldi-n-propoxysilane,bisbicycloheptenyldiisopropoxysilane, bisbicycloheptyldimethoxysilane,bisbicycloheptyldiethoxysilane, bisbicycloheptyldi-n-propoxysilane,bisbicycloheptyldiisopropoxysilane, bisadamantyldimethoxysilane,bisadamantyldiethoxysilane, bisadamantyldi-n-propoxysilane,bisadamantyldiisopropoxysilane, etc. Suitable light-absorbing monomersinclude diphenyldimethoxysilane, diphenyldiethoxysilane,methylphenyldimethoxysilane, methylphenyldiethoxysilane,diphenyldi-n-propoxysilane, and diphenyldiisopropoxysilane.

Of these, preferred are dimethyldimethoxysilane, dimethyldiethoxysilane,diethyldimethoxysilane, diethyldiethoxysilane,methylethyldimethoxysilane, methylethyldiethoxysilane,di-n-propyldimethoxysilane, di-n-butyldimethoxysilane,methylphenyldimethoxysilane, and methylphenyldiethoxysilane.

Examples of suitable monoalkoxysilanes corresponding to formula (1)wherein m1=1, m2=1 and m3=1 include trimethylmethoxysilane,trimethylethoxysilane, dimethylethylmethoxysilane, anddimethylethylethoxysilane. Suitable light-absorbing monomers includedimethylphenylmethoxysilane, dimethylphenylethoxysilane,dimethylbenzylmethoxysilane, dimethylbenzylethoxysilane,dimethylphenethylmethoxysilane, and dimethylphenethylethoxysilane.

Of these, preferred are trimethylmethoxysilane,dimethylethylmethoxysilane, dimethylphenylmethoxysilane,dimethylbenzylmethoxysilane, and dimethylphenethylmethoxysilane.

Other exemplary organic groups represented by R¹, R² and R³ includeorganic groups having at least one carbon-oxygen single bond orcarbon-oxygen double bond. Illustrative of such groups are organicgroups having at least one group selected from among epoxy, ester,alkoxy, and hydroxyl groups. Examples of organic groups having at leastone carbon-oxygen single bond or carbon-oxygen double bond in formula(1) include those of the following general formula (6).

(P-Q₁-(S₁)_(v1)-Q_(z)-)_(u)-(T)_(v2)-Q₃-(S₂)_(v3)-Q₄-   (6)

Herein, P is a hydrogen atom, hydroxyl group, epoxy ring of the formula:

C₁-C₄ alkoxy group, C₁-C₆ alkylcarbonyloxy group, or C₁-C₆ alkylcarbonylgroup; Q₁, Q₂, Q₃ and Q₄ are each independently —C_(q)H_((2q-p))P_(p)—wherein P is as defined above, p is an integer of 0 to 3, and q is aninteger of 0 to 10 (with the proviso that q=0 denotes a single bond); uis an integer of 0 to 3, S₁ and S₂ are each independently —O—, —CO—,—OCO—, —COO—, or —OCOO—; v1, v2 and v3 are each independently 0 or 1. Tis a divalent group of aliphatic or aromatic ring which may contain aheteroatom, typically oxygen, examples of which are shown below.Notably, the sites on T where T is bonded to Q₂ and Q₃ are notparticularly limited and may be selected appropriate in accordance withreactivity dependent on steric factors and the availability ofcommercial reagents used in the reaction.

Preferred examples of organic groups having at least one carbon-oxygensingle bond or carbon-oxygen double bond in formula (6) are given below.It is noted that in the following formulae, (Si) is depicted to indicatethe bonding site to silicon.

Also included in the organic groups of R¹, R² and R³ are organic groupshaving a silicon-silicon bond, examples of which are given below.

The other starting monomer is a hydrolyzable metal compound having thegeneral formula (2):

U(OR⁴)_(m4)(OR⁵)_(m5)   (2)

wherein U is an element selected from Group III, IV and V elements inthe Periodic Table, excluding silicon, R⁴ and R⁵ each are an organicgroup of 1 to 30 carbon atoms, m4 and m5 each are an integer inclusiveof 0, and m4+m5 is equal to the valence of U.

As used herein, the term “organic group” refers to a group containingcarbon, specifically carbon and hydrogen, and optionally nitrogen,oxygen, sulfur, silicon and other elements. The organic groupsrepresented by R⁴ and R⁵ include unsubstituted monovalent hydrocarbongroups, such as straight, branched or cyclic alkyl, alkenyl, alkynyl,aryl and aralkyl groups, substituted forms of the foregoing hydrocarbongroups in which one or more hydrogen atoms are substituted by epoxy,alkoxy, hydroxyl or the like, and groups which are separated by such amoiety as —O—, —CO—, —OCO—, —COO—, or —OCOO—.

Examples of suitable compounds corresponding to formula (2) wherein U isboron include such monomers as boron methoxide, boron ethoxide, boronpropoxide, boron butoxide, boron amyloxide, boron hexyloxide, boroncyclopentoxide, boron cyclohexyloxide, boron allyloxide, boronphenoxide, and boron methoxyethoxide.

Examples of suitable compounds corresponding to formula (2) wherein U isaluminum include such monomers as aluminum methoxide, aluminum ethoxide,aluminum propoxide, aluminum butoxide, aluminum amyloxide, aluminumhexyloxide, aluminum cyclopentoxide, aluminum cyclohexyloxide, aluminumallyloxide, aluminum phenoxide, aluminum methoxyethoxide, aluminumethoxyethoxide, aluminum dipropoxyethylacetoacetate, aluminumdibutoxyethylacetoacetate, aluminum propoxybisethylacetoacetate,aluminum butoxybisethylacetoacetate, aluminum 2,4-pentanedionate, andaluminum 2,2,6,6-tetramethyl-3,5-heptanedionate.

Examples of suitable compounds corresponding to formula (2) wherein U isgallium include such monomers as gallium methoxide, gallium ethoxide,gallium propoxide, gallium butoxide, gallium amyloxide, galliumhexyloxide, gallium cyclopentoxide, gallium cyclohexyloxide, galliumallyloxide, gallium phenoxide, gallium methoxyethoxide, galliumethoxyethoxide, gallium dipropoxyethylacetoacetate, galliumdibutoxyethylacetoacetate, gallium propoxybisethylacetoacetate, galliumbutoxybisethylacetoacetate, gallium 2,4-pentanedionate, and gallium2,2,6,6-tetramethyl-3,5-heptanedionate.

Examples of suitable compounds corresponding to formula (2) wherein U isyttrium include such monomers as yttrium methoxide, yttrium ethoxide,yttrium propoxide, yttrium butoxide, yttrium amyloxide, yttriumhexyloxide, yttrium cyclopentoxide, yttrium cyclohexyloxide, yttriumallyloxide, yttrium phenoxide, yttrium methoxyethoxide, yttriumethoxyethoxide, yttrium dipropoxyethylacetoacetate, yttriumdibutoxyethylacetoacetate, yttrium propoxybisethylacetoacetate, yttriumbutoxybisethylacetoacetate, yttrium 2,4-pentanedionate, and yttrium2,2,6,6-tetramethyl-3,5-heptanedionate.

Examples of suitable compounds corresponding to formula (2) wherein U isgermanium include such monomers as germanium methoxide, germaniumethoxide, germanium propoxide, germanium butoxide, germanium amyloxide,germanium hexyloxide, germanium cyclopentoxide, germaniumcyclohexyloxide, germanium allyloxide, germanium phenoxide, germaniummethoxyethoxide, and germanium ethoxyethoxide.

Examples of suitable compounds corresponding to formula (2) wherein U istitanium include such monomers as titanium methoxide, titanium ethoxide,titanium propoxide, titanium butoxide, titanium amyloxide, titaniumhexyloxide, titanium cyclopentoxide, titanium cyclohexyloxide, titaniumallyloxide, titanium phenoxide, titanium methoxyethoxide, titaniumethoxyethoxide, titanium dipropoxyethylacetoacetate, titaniumdibutoxyethylacetoacetate, titanium dipropoxide bis(2,4-pantandionate),titanium dibutoxide bis(2,4-pentanedionate).

Examples of suitable compounds corresponding to formula (2) wherein U ishafnium include such monomers as hafnium methoxide, hafnium ethoxide,hafnium propoxide, hafnium butoxide, hafnium amyloxide, hafniumhexyloxide, hafnium cyclopentoxide, hafnium cyclohexyloxide, hafniumallyloxide, hafnium phenoxide, hafnium methoxyethoxide, hafniumethoxyethoxide, hafnium dipropoxybisethylacetoacetate, hafniumdibutoxybisethylacetoacetate, hafnium dipropoxidebis(2,4-pentanedionate), and hafnium dibutoxide bis(2,4-pentanedionate).

Examples of suitable compounds corresponding to formula (2) wherein U istin include such monomers as tin methoxide, tin ethoxide, tin propoxide,tin butoxide, tin phenoxide, tin methoxyethoxide, tin ethoxyethoxide,tin 2,4-pentanedionate, and tin 2,2,6,6-tetramethyl-3,5-heptanedionate.

Examples of suitable compounds corresponding to formula (2) wherein U isarsenic include such monomers as arsenic methoxide, arsenic ethoxide,arsenic propoxide, arsenic butoxide, and arsenic phenoxide.

Examples of suitable compounds corresponding to formula (2) wherein U isantimony include such monomers as antimony methoxide, antimony ethoxide,antimony propoxide, antimony butoxide, antimony phenoxide, antimonyacetate, and antimony propionate.

Examples of suitable compounds corresponding to formula (2) wherein U isniobium include such monomers as niobium methoxide, niobium ethoxide,niobium propoxide, niobium butoxide, and nioblum phenoxide.

Examples of suitable compounds corresponding to formula (2) wherein U istantalum include such monomers as tantalum methoxide, tantalum ethoxide,tantalum propoxide, tantalum butoxide, and tantalum phenoxide.

Examples of suitable compounds corresponding to formula (2) wherein U isbismuth include such monomers as bismuth methoxide, bismuth ethoxide,bismuth propoxide, bismuth butoxide, and bismuth phenoxide.

Examples of suitable compounds corresponding to formula (2) wherein U isphosphorus include such monomers as trimethyl phosphite, triethylphosphite, tripropyl phosphite, trimethyl phosphate, triethyl phosphate,and tripropyl phosphate.

Examples of suitable compounds corresponding to formula (2) wherein U isvanadium include such monomers as vanadium oxidebis(2,4-pentanedionate), vanadium 2,4-pentanedionate, vanadiumoxytributoxide, and vanadium oxytripropoxide.

Examples of suitable compounds corresponding to formula (2) wherein U iszirconium include such monomers as zirconium methoxide, zirconiumethoxide, zirconium propoxide, zirconium butoxide, zirconium phenoxide,zirconium dibutoxide bis(2,4-pentanedionate), and zirconium dipropoxidebis(2,2,6,6-tetramethyl-3,5-heptane-dionate).

Examples of suitable compounds corresponding to formula (2) wherein U istantalum include such monomers as tantalum methoxide, tantalum ethoxide,tantalum propoxide, tantalum butoxide, and tantalum phenoxide.

By selecting one or multiple monomers from the monomers having formula(1) and one or multiple monomers from the monomers having formula (2)and combining them before or during the reaction, there is provided asystem of reactants from which the desired metal oxide-containingcompound is formed.

The metal oxide-containing compound may be prepared by subjectingselected monomers of formulae (1) and (2) to hydrolytic condensation inthe presence of an acid catalyst which is selected from mineral acids,aliphatic and aromatic sulfonic acids and mixtures thereof. Suitableacid catalysts which can be used include hydrofluoric acid, hydrochloricacid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid,phosphoric acid, methanesulfonic acid, benzenesulfonic acid, andtoluenesulfonic acid. The catalyst may be used in an amount of 10⁻⁶ to10 moles, preferably 10⁻⁵ to 5 moles, and more preferably 10⁻⁴ to 1 moleper mole of the monomers.

The amount of water used in hydrolytic condensation of the monomers toform the metal oxide-containing compound is preferably 0.01 to 100moles, more preferably 0.05 to 50 moles, even more preferably 0.1 to 30moles per mole of hydrolyzable substituent groups on the monomers. Theaddition of more than 100 moles of water is uneconomical in that theapparatus used for reaction becomes accordingly larger.

In one exemplary operating procedure, the monomers are added to anaqueous solution of the catalyst to start hydrolytic condensation. Atthis point, an organic solvent may be added to the aqueous catalystsolution and/or the lo monomers may be diluted with an organicsolvent(s). The reaction temperature is 0 to 100° C., preferably 5 to80° C. In the preferred procedure, the monomers are added dropwise at atemperature of 5 to 80° C., after which the reaction mixture is maturedat 20 to 80° C.

Examples of the organic solvent which can be added to the aqueouscatalyst solution or to the monomers for dilution include methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol,2-methyl-l-propanol, acetone, acetonitrile, tetrahydrofuran, toluene,hexane, ethyl acetate, cyclohexanone, methyl-2-n-amylketone, butane diolmonomethyl ether, propylene glycol monomethyl ether, ethylene glycolmonomethyl ether, butane diol monoethyl ether, propylene glycolmonoethyl ether, ethylene glycol monoethyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate (PGMEA), propylene glycol monoethyl etheracetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate,ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate,propylene glycol mono-tert-butyl ether acetate, γ-butyrolactone, andmixtures thereof.

Among others, water-soluble solvents are preferred. Suitablewater-soluble solvents include alcohols such as methanol, ethanol,1-propanol and 2-propanol, polyhydric alcohols such as ethylene glycoland propylene glycol, polyhydric alcohol condensation derivatives suchas butane diol monomethyl ether, propylene glycol monomethyl ether,ethylene glycol monomethyl ether, butane diol monoethyl ether, propyleneglycol monoethyl ether, ethylene glycol monoethyl ether, butane diolmonopropyl ether, propylene glycol monopropyl ether, and ethylene glycolmonopropyl ether, acetone, acetonitrile, and tetrahydrofuran. Of these,those solvents having a boiling point equal to or lower than 100° C. arepreferred.

The amount of the organic solvent used is 0 to 1,000 ml, preferably 0 to500 ml per mole of the monomers. Too much amounts of the organic solventare uneconomical in that the reactor must be of larger volume.

Thereafter, neutralization reaction of the catalyst is carried out ifnecessary, and the alcohol produced by the hydrolytic condensationreaction is removed under reduced pressure, yielding an aqueous reactionmixture. The amount of an alkaline compound used for neutralizataion ispreferably 0.1 to 2 equivalents relative to the acid used as thecatalyst. Any alkaline compound may be used as long as it exhibitsalkalinity in water.

Subsequently, the alcohol or byproducts associated with the hydrolyticcondensation reaction are preferably removed from the reaction mixture.To this end, the reaction mixture is heated at a temperature which ispreferably 0 to 100° C., more preferably 10 to 90° C., even morepreferably 15 to 80° C., although the temperature depends on the type oforganic solvent added and the type of alcohol produced. The reducedpressure is preferably atmospheric or subatmospheric, more preferablyequal to or less than 80 kPa in absolute pressure, and even morepreferably equal to or less than 50 kPa in absolute pressure, althoughthe pressure varies with the type of organic solvent and alcohol to beremoved and the vacuum pump, condenser, and heating temperature.Although an accurate determination of the amount of alcohol removed atthis point is difficult, it is desired to remove about 80% by weight ormore of the alcohol produced.

Next, the acid catalyst used in the hydrolytic condensation may beremoved from the reaction mixture. This is achieved by mixing the metaloxide-containing compound with water and extracting the metaloxide-containing compound with an organic solvent. The organic solventused herein is preferably a solvent in which the metal oxide-containingcompound is dissolvable and which provides two-layer separation whenmixed with water. Suitable organic solvents include methanol, ethanol,1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol,acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone,methyl-2-n-amylketone, butane diol monomethyl ether, propylene glycolmonomethyl ether, ethylene glycol monomethyl ether, butane diolmonoethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, ethylene glycol monopropyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propyleneglycol mono-tert-butyl ether acetate, γ-butyrolactone, methyl isobutylketone, cyclopentyl methyl ether, and mixtures thereof.

It is also acceptable to use a mixture of a water-soluble organicsolvent and a substantially water-insoluble organic solvent. Exemplarymixtures include, but are not limited to, combinations of methanol+ethylacetate, ethanol+ethyl acetate, 1-propanol+ethyl acetate,2-propanol+ethyl acetate, butane diol monomethyl ether+ethyl acetate,propylene glycol monomethyl ether+ethyl acetate, ethylene glycolmonomethyl ether+ethyl acetate, butane diol monoethyl ether+ethylacetate, propylene glycol monoethyl ether+ethyl acetate, ethylene glycolmonoethyl ether+ethyl acetate, butane diol monopropyl ether+ethylacetate, propylene glycol monopropyl ether+ethyl acetate, ethyleneglycol monopropyl ether+ethyl acetate, methanol+methyl isobutyl ketone(MIK), ethanol+MIK, 1-propanol+MIK, 2-propanol+MIK, propylene glycolmonomethyl ether+MIK, ethylene glycol monomethyl ether+MIK, propyleneglycol monoethyl ether+MIK, ethylene glycol monoethyl ether+MIK,propylene glycol monopropyl ether+MIK, ethylene glycol monopropylether+MIK, methanol+cyclopentyl methyl ether, ethanol+cyclopentyl methylether, 1-propanol+cyclopentyl methyl ether, 2-propanol+cyclopentylmethyl ether, propylene glycol monomethyl ether+cyclopentyl methylether, ethylene glycol monomethyl ether+cyclopentyl methyl ether,propylene glycol monoethyl ether+cyclopentyl methyl ether, ethyleneglycol monoethyl ether+cyclopentyl methyl ether, propylene glycolmonopropyl ether+cyclopentyl methyl ether, ethylene glycol monopropylether+cyclopentyl methyl ether, methanol+propylene glycol methyl etheracetate (PGMEA), ethanol+PGMEA, 1-propanol+PGMEA, 2-propanol+PGMEA,propylene glycol monomethyl ether+PGMEA, ethylene glycol monomethylether+PGMEA, propylene glycol monoethyl ether+PGMEA, ethylene glycolmonoethyl ether+PGMEA, propylene glycol monopropyl ether+PGMEA, andethylene glycol monopropyl ether+PGMEA.

A mixing proportion of the water-soluble organic solvent and thesubstantially water-insoluble organic solvent may be determined asappropriate although it is a usual practice to use 0.1 to 1,000 parts,preferably 1 to 500 parts, and more preferably 2 to 100 parts by weightof the water-soluble organic solvent per 100 parts by weight of thesubstantially water-insoluble organic solvent.

Subsequent step is to wash with neutral water. The water used forwashing may be deionized water or ultrapure water. The amount of wateris 0.01 to 100 liters (L), preferably 0.05 to 50 L, more preferably 0.1to 5 L per liter of the metal oxide-containing compound solution. Thewashing step may be carried out by feeding both the liquids into acommon vessel, agitating the contents, allowing the mixture to stand andto separate into two layers, and removing the water layer. The number ofwashing steps may be one or more, although the repetition of more than10 washing steps does not achieve the effect corresponding to such anumber of steps. Preferably the number of washing steps is from 1 toabout 5.

Other methods of removing the acid catalyst include the use of anion-exchange resin, and neutralization with epoxy compounds such asethylene oxide and propylene oxide followed by removal. A proper methodmay be selected from among these methods in accordance with the acidcatalyst used in the reaction.

As used herein, the term “substantially removing the acid catalyst”means that it is acceptable that no more than 10% by weight, preferablyno more than 5% by weight of the acid catalyst used in the reaction isleft in the metal oxide-containing compound.

Since the water washing operation may sometimes achieve an effectsubstantially equivalent to a fractionation operation in that part ofthe metal oxide-containing compound is carried away to the water layer,the number of washing cycles and the amount of water may be determinedappropriate depending on the relative extent of catalyst removal andfractionation effects.

A final solvent is added to the metal oxide-containing compound solutionfrom which the acid catalyst may or may not have been removed, forinducing solvent exchange under a reduced pressure, yielding asilicon-containing compound solution. The temperature for solventexchange is preferably 0 to 100° C., more preferably 10 to 90° C., evenmore preferably 15 to 80° C., although the temperature depends on thetype of reaction or extraction solvent to be removed. The reducedpressure is preferably atmospheric or subatmospheric, more preferablyequal to or less than 80 kPa in absolute pressure, and even morepreferably equal to or less than 50 kPa in absolute pressure, althoughthe pressure varies with the type of extraction solvent to be removedand the vacuum pump, condenser, and heating temperature.

As a result of solvent exchange, the metal oxide-containing compoundsometimes becomes unstable. Such instability occurs depending on thecompatibility of the metal oxide-containing compound with the finalsolvent. Component (C) to be described later may be added as astabilizer in order to prevent such inconvenience. The amount ofcomponent (C) added is 0 to 25 parts, preferably 0 to 15 parts, morepreferably 0 to 5 parts by weight per 100 parts by weight of the metaloxide-containing compound in the solution prior to the solvent exchange.When added, the preferred amount of component (C) is at least 0.5 partby weight. If necessary for the solution before the solvent exchange,component (C) may be added before the solvent exchange operation iscarried out.

If the metal oxide-containing compound is concentrated above a certainlevel, it undergoes condensation reaction so that it converts to thestate which can no longer be re-dissolved in organic solvents. It isthen recommended that the metal oxide-containing compound be kept insolution form at an adequate concentration. Too low a concentrationcorresponds to an excessive volume of solvent which is uneconomical. Aconcentration of 0.1 to 20% by weight is preferable.

The final solvent added to the metal oxide-containing compound solutionis preferably an alcoholic solvent, examples of which include monoalkylethers of ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, dipropylene glycol and the like. Preferred examplesinclude butane diol monomethyl ether, propylene glycol monomethyl ether,ethylene glycol monomethyl ether, butane diol monoethyl ether, propyleneglycol monoethyl ether, ethylene glycol monoethyl ether, butane diolmonopropyl ether, propylene glycol monopropyl ether, and ethylene glycolmonopropyl ether.

In another exemplary reaction procedure, water or a water-containingorganic solvent is added to the monomers or an organic solvent solutionof the monomers to start hydrolytic reaction. At this point, thecatalyst may be added to the monomers or an organic solvent solution ofthe monomers, or water or a water-containing organic solvent. Thereaction temperature is 0 to 100° C., preferably 10 to 80° C. In thepreferred procedure, water is added dropwise at a temperature of 10 to50° C., after which the reaction mixture is matured at 20 to 80° C.

Of the organic solvents, if used, water-soluble solvents are preferred.Suitable organic solvents include methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone,tetrahydrofuran, acetonitrile, and polyhydric alcohol condensationderivatives such as butane diol monomethyl ether, propylene glycolmonomethyl ether, ethylene glycol monomethyl ether, butane diolmonoethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, ethylene glycol monopropyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate, andpropylene glycol monopropyl ether, and mixtures thereof.

The amount of the organic solvent used may be the same as describedabove for the one procedure. The resulting reaction mixture ispost-treated as described above for the one procedure, yielding a metaloxide-containing compound.

The molecular weight of the resulting metal oxide-containing compoundmay be adjusted by a choice of monomers and by control of reactionconditions during polymerization. Compounds having a weight averagemolecular weight in excess of 100,000 may produce foreign matter orcoating specks in some cases. Then the metal oxide-containing compoundpreferably has a weight average molecular weight equal to or less than100,000, more preferably 200 to 50,000, and even more preferably 300 to30,000. It is noted that the weight average molecular weight isdetermined by gel permeation chromatography (GPC) using an RI detectorand polystyrene standards.

In the metal oxide-containing film-forming composition of the invention,two or more metal oxide-containing compounds which differ in compositionand/or reaction conditions may be contained as long as they are preparedunder acidic conditions.

According to the invention, a metal oxide-containing film-formingcomposition is formulated by combining (A) the metal oxide-containingcompound defined above with (B) a thermal crosslink accelerator, (C) anacid, and (D) an organic solvent.

Component B

The composition of the invention must contain a thermal crosslinkaccelerator as component (B) to further accelerate crosslinking reactionin forming a metal oxide-containing film. Included in the acceleratorare compounds having the general formulae (3) and (4).

L_(a)H_(b)X   (3)

Herein L is lithium, sodium, potassium, rubidium or cesium, X is ahydroxyl group or a mono or polyfunctional organic acid residue of 1 to30 carbon atoms, “a” is an integer of at least 1, “b” is 0 or an integerof at least 1, and a+b is equal to the valence of hydroxyl group ororganic acid residue.

M_(a)H_(b)A   (4)

Herein M is sulfonium, iodonium or ammonium, preferably tertiarysulfonium, secondary iodonium, or quaternary ammonium, and morepreferably a photo-degradable onium like triarylsulfonium ordiaryliodonium. A is as defined above for X or a non-nucleophiliccounter ion, “a” and “b” are as defined above, and a+b is equal to thevalence of hydroxyl group, organic acid residue or non-nucleophiliccounter ion.

Exemplary of the compound of formula (3) are alkali metal salts oforganic acids, for example, salts of lithium, sodium, potassium,rubidium and cesium with hydroxide, formic acid, acetic acid, propionicacid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid,octanoic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid,linoleic acid, linolenic acid, benzoic acid, phthalic acid, isophthalicacid, terephthalic acid, salicylic acid, trifluoroacetic acid,monochloroacetic acid, dichloroacetic acid, trichloroacetic acid andother monofunctional acids; and salts of lithium, sodium, potassium,rubidium and cesium with mono- or di-functional acids such as oxalicacid, malonic acid, methylmalonic acid, ethylmalonic acid, propylmalonicacid, butylmalonic acid, dimethylmalonic acid, diethylmalonic acid,succinic acid, methylsuccinic acid, glutaric acid, adipic acid, itaconicacid, maleic acid, fumaric acid, citraconic acid, citric acid, andcarbonic acid.

Illustrative examples include lithium formate, lithium acetate, lithiumpropionate, lithium butanoate, lithium pentanoate, lithium hexanoate,lithium heptanoate, lithium octanoate, lithium nonanoate, lithiumdecanoate, lithium oleate, lithium stearate, lithium linoleate, lithiumlinolenate, lithium benzoate, lithium phthalate, lithium isophthalate,lithium terephthalate, lithium salicylate, lithium trifluoroacetate,lithium monochloroacetate, lithium dichloroacetate, lithiumtrichloroacetate, lithium hydroxide, lithium hydrogen oxalate, lithiumhydrogen malonate, lithium hydrogen methylmalonate, lithium hydrogenethylmalonate, lithium hydrogen propylmalonate, lithium hydrogenbutylmalonate, lithium hydrogen dimethylmalonate, lithium hydrogendiethylmalonate, lithium hydrogen succinate, lithium hydrogenmethylsuccinate, lithium hydrogen glutarate, lithium hydrogen adipate,lithium hydrogen itaconate, lithium hydrogen maleate, lithium hydrogenfumarate, lithium hydrogen citraconate, lithium hydrogen citrate,lithium hydrogen carbonate, lithium oxalate, lithium malonate, lithiummethylmalonate, lithium ethylmalonate, lithium propylmalonate, lithiumbutylmalonate, lithium dimethylmalonate, lithium diethylmalonate,lithium succinate, lithium methylsuccinate, lithium glutarate, lithiumadipate, lithium itaconate, lithium maleate, lithium fumarate, lithiumcitraconate, lithium citrate, lithium carbonate;

sodium formate, sodium acetate, sodium propionate, sodium butanoate,sodium pentanoate, sodium hexanoate, sodium heptanoate, sodiumoctanoate, sodium nonanoate, sodium decanoate, sodium oleate, sodiumstearate, sodium linoleate, sodium linolenate, sodium benzoate, sodiumphthalate, sodium isophthalate, sodium terephthalate, sodium salicylate,sodium trifluoroacetate, sodium monochloroacetate, sodiumdichloroacetate, sodium trichloroacetate, sodium hydroxide, sodiumhydrogen oxalate, sodium hydrogen malonate, sodium hydrogenmethylmalonate, sodium hydrogen ethylmalonate, sodium hydrogenpropylmalonate, sodium hydrogen butylmalonate, sodium hydrogendimethylmalonate, sodium hydrogen diethylmalonate, sodium hydrogensuccinate, sodium hydrogen methylsuccinate, sodium hydrogen glutarate,sodium hydrogen adipate, sodium hydrogen itaconate, sodium hydrogenmaleate, sodium hydrogen fumarate, sodium hydrogen citraconate, sodiumhydrogen citrate, sodium hydrogen carbonate, sodium oxalate, sodiummalonate, sodium methylmalonate, sodium ethylmalonate, sodiumpropylmalonate, sodium butylmalonate, sodium dimethylmalonate, sodiumdiethylmalonate, sodium succinate, sodium methylsuccinate, sodiumglutarate, sodium adipate, sodium itaconate, sodium maleate, sodiumfumarate, sodium citraconate, sodium citrate, sodium carbonate;

potassium formate, potassium acetate, potassium propionate, potassiumbutanoate, potassium pentanoate, potassium hexanoate, potassiumheptanoate, potassium octanoate, potassium nonanoate, potassiumdecanoate, potassium oleate, potassium stearate, potassium linoleate,potassium linolenate, potassium benzoate, potassium phthalate, potassiumisophthalate, potassium terephthalate, potassium salicylate, potassiumtrifluoroacetate, potassium monochloroacetate, potassiumdichloroacetate, potassium trichloroacetate, potassium hydroxide,potassium hydrogen oxalate, potassium hydrogen malonate, potassiumhydrogen methylmalonate, potassium hydrogen ethylmalonate, potassiumhydrogen propylmalonate, potassium hydrogen butylmalonate, potassiumhydrogen dimethylmalonate, potassium hydrogen diethylmalonate, potassiumhydrogen succinate, potassium hydrogen methylsuccinate, potassiumhydrogen glutarate, potassium hydrogen adipate, potassium hydrogenitaconate, potassium hydrogen maleate, potassium hydrogen fumarate,potassium hydrogen citraconate, potassium hydrogen citrate, potassiumhydrogen carbonate, potassium oxalate, potassium malonate, potassiummethylmalonate, potassium ethylmalonate, potassium propylmalonate,potassium butylmalonate, potassium dimethylmalonate, potassiumdiethylmalonate, potassium succinate, potassium methylsuccinate,potassium glutarate, potassium adipate, potassium itaconate, potassiummaleate, potassium fumarate, potassium citraconate, potassium citrate,potassium carbonate, etc.

The compounds of formula (4) include sulonium, iodonium and ammoniumcompounds having the formulae (Q-1), (Q-2), and (Q-3), respectively.

Herein. R²⁰⁴, R²⁰⁵ and R²⁰⁶ are each independently a straight, branchedor cyclic alkyl, alkenyl, oxoalkyl or oxoalkenyl group of 1 to 12 carbonatoms, substituted or unsubstituted aryl group of 6 to 20 carbon atoms,aralkyl or aryloxoalkyl group of 7 to 12 carbon atoms, in which some orall hydrogen atoms may be substituted by alkoxy groups or the like. Apair of R²⁰⁵ and R²⁰⁶ may form a ring with the sulfur atom to which theyare attached, and each is a C₁-C₆ alkylene group when they form a ring.A⁻ is a non-nucleophilic counter ion. R²⁰⁷, R²⁰⁸, R²⁰⁹, and R²¹⁰ are asdefined for R²⁰⁴, R²⁰⁵ and R²⁰⁶, and may also be hydrogen. A pair ofR²⁰⁷ and R²⁰⁸ or a combination of R²⁰⁷, R²⁰⁸ and R²⁰⁹ may form a ringwith the nitrogen atom to which they are attached, and each is a C₃-C₁₀alkylene group when they form a ring.

R²⁰⁴, R²⁰⁵ , R²⁰⁶, R²⁰⁷, R²⁰⁸ , R²⁰⁹ , and R²¹⁰ may be the same ordifferent. Suitable alkyl groups include methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl,4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl. Suitablealkenyl groups include vinyl, allyl, propenyl, butenyl, hexenyl, andcyclohexenyl. Suitable oxoalkyl groups include 2-oxocyclopentyl and2-oxocyclohexyl as well as 2-oxopropyl, 2-cyclopentyl-2-oxoethyl,2-cyclohexyl-2-oxoethyl, and 2-(4-methylcyclohexyl)-2-oxoethyl. Suitablearyl groups include phenyl and naphthyl, alkoxyphenyl groups such asp-methoxyphenyl, m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl,p-tert-butoxyphenyl, and m-tert-butoxyphenyl, alkylphenyl groups such as2-methylphenyl, 3-methylphenyl, 4-methylphenyl, ethylphenyl,4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl, alkylnaphthylgroups such as methylnaphthyl and ethylnaphthyl, alkoxynaphthyl groupssuch as methoxynaphthyl and ethoxynaphthyl, dialkylnaphthyl groups suchas dimethylnaphthyl and diethylnaphthyl, and dialkoxynaphthyl groupssuch as dimethoxynaphthyl and diethoxynaphthyl. Suitable aralkyl groupsinclude benzyl, phenylethyl and phenethyl. Suitable aryloxoalkyl groupsinclude 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl and 2-(2-naphthyl)-2-oxoethyl.

Examples of the non-nucleophilic counter ion represented by A⁻ includehydroxyl, formate, acetate, propionate, butanoate, pentanoate,hexanoate, heptanoate, octanoate, nonanoate, decanoate, oleate,stearate, linoleate, linolenate, benzoate, p-methylbenzoate,p-t-butylbenzoate, phthalate, isophthalate, terephthalate, salicylate,trifluoroacetate, monochloroacetate, dichloroacetate, trichloroacetate,fluoride, chloride, bromide, iodide, nitrate, chlorate, perchlorate,bromate, iodate, oxalate, malonate, methylmalonate, ethylmalonate,propylmalonate, butylmalonate, dimethylmalonate, diethylmalonate,succinate, methylsuccinate, glutarate, adipate, itaconate, maleate,fumarate, citraconate, citrate, and carbonate ions.

Specifically, suitable sulfonium compounds include triphenylsulfoniumformate, triphenylsulfonium acetate, triphenylsulfonium propionate,triphenylsulfonium butanoate, triphenylsulfonium pentanoate,triphenylsulfonium hexanoate, triphenylsulfonium heptanoate,triphenylsulfonium octanoate, triphenylsulfonium nonanoate,triphenylsulfonium decanoate, triphenylsulfonium oleate,triphenylsulfonium stearate, triphenylsulfonium linoleate,triphenylsulfonium linolenate, triphenylsulfonium benzoate,triphenylsulfonium p-methylbenzoate, triphenylsulfoniump-t-butylbenzoate, triphenylsulfonium phthalate, triphenylsulfoniumisophthalate, triphenylsulfonium terephthalate, triphenylsulfoniumsalicylate, triphenylsulfonium trifluoroacetate, triphenylsulfoniummonochloroacetate, triphenylsulfonium dichloroacetate,triphenylsulfonium trichloroacetate, triphenylsulfonium hydroxide,triphenylsulfonium oxalate, triphenylsulfonium malonate,triphenylsulfonium methylmalonate, triphenylsulfonium ethylmalonate,triphenylsulfonium propylmalonate, triphenylsulfonium butylmalonate,triphenylsulfonium dimethylmalonate, triphenylsulfonium diethylmalonate,triphenylsulfonium succinate, triphenylsulfonium methylsuccinate,triphenylsulfonium glutarate, triphenylsulfonium adipate,triphenylsulfonium itaconate, triphenylsulfonium maleate,triphenylsulfonium fumarate, triphenylsulfonium citraconate,triphenylsulfonium citrate, triphenylsulfonium carbonate,triphenylsulfonium chloride, triphenylsulfonium bromide,triphenylsulfonium iodide, triphenylsulfonium nitrate,triphenylsulfonium chlorate, triphenylsulfonium perchlorate,triphenylsulfonium bromate, triphenylsulfonium iodate,bistriphenylsulfonium oxalate, bistriphenylsulfonium malonate,bistriphenylsulfonium methylmalonate, bistriphenylsulfoniumethylmalonate, bistriphenylsulfonium propylmalonate,bistriphenylsulfonium butylmalonate, bistriphenylsulfoniumdimethylmalonate, bistriphenylsulfonium diethylmalonate,bistriphenylsulfonium succinate, bistriphenylsulfonium methylsuccinate,bistriphenylsulfonium glutarate, bistriphenylsulfonium adipate,bistriphenylsulfonium itaconate, bistriphenylsulfonium maleate,bistriphenylsulfonium fumarate, bistriphenylsulfonium citraconate,bistriphenylsulfonium citrate, and bistriphenylsulfonium carbonate.

Suitable iodonium compounds include diphenyliodonium formate,diphenyliodonium acetate, diphenyliodonium propionate, diphenyliodoniumbutanoate, diphenyliodonium pentanoate, diphenyliodonium hexanoate,diphenyliodonium heptanoate, diphenyliodonium octanoate,diphenyliodonium nonanoate, diphenyliodonium decanoate, diphenyliodoniumoleate, diphenyliodonium stearate, diphenyliodonium linoleate,diphenyliodonium linolenate, diphenyliodonium benzoate, diphenyliodoniump-methylbenzoate, diphenyliodonium p-t-butylbenzoate, diphenyliodoniumphthalate, diphenyliodonium isophthalate, diphenyliodoniumterephthalate, diphenyliodonium salicylate, diphenyliodoniumtrifluoroacetate, diphenyliodonium monochloroacetate, diphenyliodoniumdichloroacetate, diphenyliodonium trichloroacetate, diphenyliodoniumhydroxide, diphenyliodonium oxalate, diphenyliodonium malonate,diphenyliodonium methylmalonate, diphenyliodonium ethylmalonate,diphenyliodonium propylmalonate, diphenyliodonium butylmalonate,diphenyliodonium dimethylmalonate, diphenyliodonium diethylmalonate,diphenyliodonium succinate, diphenyliodonium methylsuccinate,diphenyliodonium glutarate, diphenyliodonium adipate, diphenyliodoniumitaconate, diphenyliodonium maleate, diphenyliodonium fumarate,diphenyliodonium citraconate, diphenyliodonium citrate, diphenyliodoniumcarbonate, diphenyliodonium chloride, diphenyliodonium bromide,diphenyliodonium iodide, diphenyliodonium nitrate, diphenyliodoniumchlorate, diphenyliodonium perchlorate, diphenyliodonium bromate,diphenyliodonium iodate, bisdiphenyliodonium oxalate,bisdiphenyliodonium malonate, bisdiphenyliodonium methylmalonate,bisdiphenyliodonium ethylmalonate, bisdiphenyliodonium propylmalonate,bisdiphenyliodonium butylmalonate, bisdiphenyliodonium dimethylmalonate,bisdiphenyliodonium diethylmalonate, bisdiphenyliodonium succinate,bisdiphenyliodonium methylsuccinate, bisdiphenyliodonium glutarate,bisdiphenyliodonium adipate, bisdiphenyliodonium itaconate,bisdiphenyliodonium maleate, bisdiphenyliodonium fumarate,bisdiphenyliodonium citraconate, bisdiphenyliodonium citrate, andbisdiphenyliodonium carbonate.

Suitable ammonium compounds include tetramethylammonium formate,tetramethylammonium acetate, tetramethylammonium propionate,tetramethylammonium butanoate, tetramethylammonium pentanoate,tetramethylammonium hexanoate, tetramethylammonium heptanoate,tetramethylammonium octanoate, tetramethylammonium nonanoate,tetramethylammonium decanoate, tetramethylammonium oleate,tetramethylammonium stearate, tetramethylammonium linoleate,tetramethylammonium linolenate, tetramethylammonium benzoate,tetramethylammonium p-methylbenzoate, tetramethylammoniump-t-butylbenzoate, tetramethylammonium phthalate, tetramethylammoniumisophthalate, tetramethylammonium terephthalate, tetramethylammoniumsalicylate, tetramethylammonium trifluoroacetate, tetramethylammoniummonochloroacetate, tetramethylammonium dichloroacetate,tetramethylammonium trichloroacetate, tetramethylammonium hydroxide,tetramethylammonium oxalate, tetramethylammonium malonate,tetramethylammonium methylmalonate, tetramethylammonium ethylmalonate,tetramethylammonium propylmalonate, tetramethylammonium butylmalonate,tetramethylammonium dimethylmalonate, tetramethylammoniumdiethylmalonate, tetramethylammonium succinate, tetramethylammoniummethylsuccinate, tetramethylammonium glutarate, tetramethylammoniumadipate, tetramethylammonium itaconate, tetramethylammonium maleate,tetramethylammonium fumarate, tetramethylammonium citraconate,tetramethylammonium citrate, tetramethylammonium carbonate,tetramethylammonium chloride, tetramethylammonium bromide,tetramethylammonium iodide, tetramethylammonium nitrate,tetramethylammonium chlorate, tetramethylammonium perchlorate,tetramethylammonium bromate, tetramethylammonium iodate,bistetramethylammonium oxalate, bistetramethylammonium malonate,bistetramethylammonium methylmalonate, bistetramethylammoniumethylmalonate, bistetramethylammonium propylmalonate,bistetramethylammonium butylmalonate, bistetramethylammoniumdimethylmalonate, bistetramethylammonium diethylmalonate,bistetramethylammonium succinate, bistetramethylammoniummethylsuccinate, bistetramethylammonium glutarate,bistetramethylammonium adipate, bistetramethylammonium itaconate,bistetramethylammonium maleate, bistetramethylammonium fumarate,bistetramethylammonium citraconate, bistetramethylammonium citrate,bistetramethylammonium carbonate; tetrapropylammonium formate,tetrapropylammonium acetate, tetrapropylammonium propionate,tetrapropylammonium butanoate, tetrapropylammonium pentanoate,tetrapropylammoniurn hexanoate, tetrapropylammonium heptanoate,tetrapropylammonium octanoate, tetrapropylammonium nonanoate,tetrapropylammonium decanoate, tetrapropylammonium oleate,tetrapropylammonium stearate, tetrapropylammonium linoleate,tetrapropylammonium linolenate, tetrapropylammonium benzoate,tetrapropylammonium p-methylbenzoate, tetrapropylammoniump-t-butylbenzoate, tetrapropylammonium phthalate, tetrapropylammoniumisophthalate, tetrapropylammonium terephthalate, tetrapropylammoniumsalicylate, tetrapropylammonium trifluoroacetate, tetrapropylammoniummonochloroacetate, tetrapropylammonium dichloroacetate,tetrapropylammonium trichloroacetate, tetrapropylammonium hydroxide,tetrapropylammonium oxalate, tetrapropylammonium malonate,tetrapropylammonium methylmalonate, tetrapropylammonium ethylmalonate,tetrapropylammonium propylmalonate, tetrapropylammonium butylmalonate,tetrapropylammonium dimethylmalonate, tetrapropylammoniumdiethylmalonate, tetrapropylammonium succinate, tetrapropylammoniummethylsuccinate, tetrapropylammonium glutarate, tetrapropylammoniumadipate, tetrapropylammonium itaconate, tetrapropylammonium maleate,tetrapropylammonium fumarate, tetrapropylammonium citraconate,tetrapropylammonium citrate, tetrapropylammonium carbonate,tetrapropylammonium chloride, tetrapropylammonium bromide,tetrapropylammonium iodide, tetrapropylammonium nitrate,tetrapropylammonium chlorate, tetrapropylammonium perchlorate,tetrapropylammonium bromate, tetrapropylammonium iodate,bistetrapropylammonium oxalate, bistetrapropylammonium malonate,bistetrapropylammonium methylmalonate, bistetrapropylammoniumethylmalonate, bistetrapropylammonium propylmalonate,bistetrapropylammonium butylmalonate, bistetrapropylammoniumdimethylmalonate, bistetrapropylammonium diethylmalonate,bistetrapropylammonium succinate, bistetrapropylammoniummethylsuccinate, bistetrapropylammonium glutarate,bistetrapropylammonium adipate, bistetrapropylammonium itaconate,bistetrapropylammonium maleate, bistetrapropylammonium fumarate,bistetrapropylammonium citraconate, bistetrapropylammonium citrate,bistetrapropylammonium carbonate; and tetrabutylammonium formate,tetrabutylammonium acetate, tetrabutylammonium propionate,tetrabutylammonium butanoate, tetrabutylammonium pentanoate,tetrabutylammonium hexanoate, tetrabutylammonium heptanoate,tetrabutylammonium octanoate, tetrabutylammonium nonanoate,tetrabutylammonium decanoate, tetrabutylammonium oleate,tetrabutylammonium stearate, tetrabutylammonium linoleate,tetrabutylammonium linolenate, tetrabutylammonium benzoate,tetrabutylammonium p-methylbenzoate, tetrabutylammoniump-t-butylbenzoate, tetrabutylammonium phthalate, tetrabutylammoniumisophthalate, tetrabutylammonium terephthalate, tetrabutylammoniumsalicylate, tetrabutylammonium trifluoroacetate, tetrabutylammoniummonochloroacetate, tetrabutylammonium dichloroacetate,tetrabutylammonium trichloroacetate, tetrabutylammonium hydroxide,tetrabutylammonium oxalate, tetrabutylammonium malonate,tetrabutylammonium methylmalonate, tetrabutylammonium ethylmalonate,tetrabutylammonium propylmalonate, tetrabutylammonium butylmalonate,tetrabutylammonium dimethylmalonate, tetrabutylammonium diethylmalonate,tetrabutylammonium succinate, tetrabutylammonium methylsuccinate,tetrabutylammonium glutarate, tetrabutylammonium adipate,tetrabutylammonium itaconate, tetrabutylammonium maleate,tetrabutylammonium fumarate, tetrabutylammonium citraconate,tetrabutylammonium citrate, tetrabutylammonium carbonate,tetrabutylammonium chloride, tetrabutylammonium bromide,tetrabutylammonium iodide, tetrabutylammonium nitrate,tetrabutylammonium chlorate, tetrabutylammonium perchlorate,tetrabutylammonium bromate, tetrabutylammonium iodate,bistetrabutylammonium oxalate, bistetrabutylammonium malonate,bistetrabutylammonium methylmalonate, bistetrabutylammoniumethylmalonate, bistetrabutylammonium propylmalonate,bistetrabutylammonium butylmalonate, bistetrabutylammoniumdimethylmalonate, bistetrabutylammonium diethylmalonate,bistetrabutylammonium succinate, bistetrabutylammonium methylsuccinate,bistetrabutylammonium glutarate, bistetrabutylammonium adipate,bistetrabutylammonium itaconate, bistetrabutylammonium maleate,bistetrabutylammonium fumarate, bistetrabutylammonium citraconate,bistetrabutylammonium citrate, and bistetrabutylammonium carbonate.

The thermal crosslink accelerators may be used alone or in admixture oftwo or more. An appropriate amount of the thermal crosslink acceleratoradded is 0.01 to 50 parts, more preferably 0.1 to 40 parts by weight per100 parts by weight of the base polymer. As used herein, the “basepolymer” refers to the metal oxide-containing compound (A) obtained bythe above-described method.

Component C

A mono or polyfunctional organic acid of 1 to 30 carbon atoms must beadded to the heat-curable metal oxide-containing film-formingcomposition as component (C) in order to keep the composition stable.Suitable organic acids include, but are not limited to, formic acid,acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoicacid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleicacid, stearic acid, linoleic acid, linolenic acid, benzoic acid,phthalic acid, isophthalic acid, terephthalic acid, salicylic acid,trifluoroacetic acid, monochloroacetic acid, dichloroacetic acid,trichloroacetic acid, oxalic acid, malonic acid, methylmalonic acid,ethylmalonic acid, propylmalonic acid, butylmalonic acid,dimethylmalonic acid, diethylmalonic acid, succinic acid, methylsuccinicacid, glutaric acid, adipic acid, itaconic acid, maleic acid, fumaricacid, citraconic acid, and citric acid. Of these, oxalic acid, maleicacid, formic acid, acetic acid, propionic acid, and citric acid arepreferred. A mixture of two or more acids may be used to maintain thestability.

The amount of the acid added is 0.001 to 25 parts, preferably 0.01 to 15parts, and more preferably 0.1 to 5 parts by weight per 100 parts byweight of the metal oxide-containing compound in the composition.Alternatively, the organic acid is added in such amounts that thecomposition may be at a proper pH, preferably 0≦pH 5 7, more preferably0.3≦pH≦6.5, and even more preferably 0.5≦pH≦6.

Component D

In the composition comprising the metal oxide-containing compoundaccording to the invention, an organic solvent is present as component(D). It may be the same as used in the preparation of the metaloxide-containing compounds. Water-soluble organic solvents arepreferred. Examples of the solvent used include monoalkyl ethers ofethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, butane diol, pentane diol, etc. The organicsolvent is preferably selected from among butane diol monomethyl ether,propylene glycol monomethyl ether, ethylene glycol monomethyl ether,butane diol monoethyl ether, propylene glycol monoethyl ether, ethyleneglycol monoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, and ethylene glycol monopropyl ether. The amount ofthe organic solvent used will be described later.

Component E

In a preferred embodiment, the composition may further comprise (E) asilicon-containing compound obtained through hydrolytic condensation ofone or multiple hydrolyzable silicon compounds having the generalformula (5):

R⁶ _(m6)R⁷ _(m7)R⁸ _(m8)Si(OR⁹)_((4-m6-m7-m8))   (5)

wherein R⁹ is an alkyl group of 1 to 6 carbon atoms, R⁶, R⁷ and R⁸ eachare hydrogen or a monovalent organic group of 1 to 30 carbon atoms, m6,m7 and m8 each are 0 or 1, and m6+m7+m8 is an integer of 0 to 3.

R⁶, R⁷, R⁸, R⁹, m6, m7, and m8 in formula (5) correspond to R¹, R², R³,R, m1, m2, and m3 in formula (1), and include the same examples.

The silicon-containing compound (E) may be prepared by the same methodas component (A).

Alternatively, the silicon-containing compound (E) may be preparedthrough hydrolytic condensation of a monomer in the presence of a basecatalyst. The preferred method of preparing the silicon-containingcompound is exemplified below, but not limited thereto.

The starting material or monomer may be of formula (5) which has beengenerally described and specifically illustrated above.

The silicon-containing compound may be prepared by subjecting a suitablemonomer(s) to hydrolytic condensation in the presence of a basiccatalyst.

Suitable basic catalysts which can be used herein include, but are notlimited to, methylamine, ethylamine, propylamine, butylamine,ethylenediamine, hexamethylenediamine, dimethylamine, diethylamine,ethylmethylamine, trimethylamine, triethylamine, tripropylamine,tributylamine, cyclohexylamine, dicyclohexylamine, monoethanolamine,diethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine,triethanolamine, diazabicyclooctane, diazabicyclocyclononene,diazabicycloundecene, hexamethylenetetramine, aniline,N,N-dimethylaniline, pyridine, N,N-dimethylaminopyridine, pyrrole,piperazine, pyrrolidine, piperidine, picoline, tetramethylammoniumhydroxide, choline hydroxide, tetrapropylammonium hydroxide,tetrabutylammonium hydroxide, ammonia, lithium hydroxide, sodiumhydroxide, potassium hydroxide, barium hydroxide, and calcium hydroxide.The catalyst may be used in an amount of 10⁻⁶ to 10 moles, preferably10⁻⁵ to 5 moles, and more preferably 10⁻⁴ to 1 mole per mole of thesilicon monomer(s).

The amount of water used in hydrolytic condensation of the monomer(s) toform the silicon-containing compound is preferably 0.1 to 50 moles permole of hydrolyzable substituent group(s) on the monomer(s). Theaddition of more than 50 moles of water is uneconomical in that theapparatus used for reaction becomes accordingly larger.

In one exemplary operating procedure, the monomer is added to an aqueoussolution of the catalyst to start hydrolytic condensation. At thispoint, an organic solvent may be added to the aqueous catalyst solutionand/or the monomer may be diluted with an organic solvent. The reactiontemperature is 0 to 100° C., preferably 5 to 80° C. In the preferredprocedure, the monomer is added dropwise at a temperature of 5 to 80°C., after which the reaction mixture is matured at 20 to 80° C.

Examples of the organic solvent which can be added to the aqueouscatalyst solution or to the monomer for dilution include methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol,2-methyl-1-propanol, acetone, acetonitrile, tetrahydrofuran, toluene,hexane, ethyl acetate, cyclohexanone, methyl-2-n-amylketone, propyleneglycol monomethyl ether, ethylene glycol monomethyl ether, propyleneglycol monoethyl ether, ethylene glycol monoethyl ether, propyleneglycol dimethyl ether, diethylene glycol dimethyl ether, propyleneglycol monomethyl ether acetate (PGMEA), propylene glycol monoethylether acetate, ethyl pyruvate, butyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate,tert-butyl propionate, propylene glycol mono-tert-butyl ether acetate,γ-butyrolactone, and mixtures thereof.

Among others, water-soluble solvents are preferred. Suitablewater-soluble solvents include alcohols such as methanol, ethanol,1-propanol and 2-propanol, polyhydric alcohols such as ethylene glycoland propylene glycol, polyhydric alcohol condensation derivatives suchas propylene glycol monomethyl ether, ethylene glycol monomethyl ether,propylene glycol monoethyl ether, ethylene glycol monoethyl ether,propylene glycol monopropyl ether, and ethylene glycol monopropyl ether,acetone, acetonitrile, and tetrahydrofuran. Of these, those solventshaving a boiling point equal to or lower than 100° C. are preferred.

The amount of the organic solvent used is preferably 0 to 1,000 ml permole of the monomer. Too much amounts of the organic solvent areuneconomical in that the reactor must be of larger volume.

Thereafter, neutralization reaction of the catalyst is carried out ifnecessary, and the alcohol produced by the hydrolytic condensationreaction is removed under reduced pressure, yielding an aqueous reactionmixture. The amount of an acidic compound used for neutralizataion ispreferably 0.1 to 2 equivalents relative to the base used as thecatalyst. Any acidic compound may be used as long as it exhibits acidityin water.

Subsequently, the alcohol produced by the hydrolytic condensationreaction must be removed from the reaction mixture. To this end, thereaction mixture is heated at a temperature which is preferably 0 to100° C., more preferably 10 to 90° C., even more preferably 15 to 80°C., although the temperature depends on the type of organic solventadded and the type of alcohol produced. The reduced pressure ispreferably atmospheric or subatmospheric, more preferably equal to orless than 80 kPa in absolute pressure, and even more preferably equal toor less than 50 kPa in absolute pressure, although the pressure varieswith the type of organic solvent and alcohol to be removed and thevacuum pump, condenser, and heating temperature. Although an accuratedetermination of the amount of alcohol removed at this point isdifficult, it is desired to remove about 80% by weight or more of thealcohol produced.

Next, the basic catalyst used in the hydrolytic condensation is removedfrom the reaction mixture. This is achieved by extracting thesilicon-containing compound with an organic solvent. The organic solventused herein is preferably a solvent in which the silicon-containingcompound is dissolvable and which provides two-layer separation whenmixed with water. Suitable organic solvents include methanol, ethanol,1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol,acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone,methyl-2-n-amylketone, propylene glycol monomethyl ether, ethyleneglycol monomethyl ether, propylene glycol monoethyl ether, ethyleneglycol monoethyl ether, propylene glycol monopropyl ether, ethyleneglycol monopropyl ether, propylene glycol dimethyl ether, diethyleneglycol dimethyl ether, propylene glycol monomethyl ether acetate,propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate,methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butylacetate, tert-butyl propionate, propylene glycol mono-tert-butyl etheracetate, γ-butyrolactone, methyl isobutyl ketone, cyclopentyl methylether, and mixtures thereof.

It is also acceptable to use a mixture of a water-soluble organicsolvent and a substantially water-insoluble organic solvent. Exemplarymixtures include, but are not limited to, combinations of methanol+ethylacetate, ethanol+ethyl acetate, 1-propanol+ethyl acetate,2-propanol+ethyl acetate, propylene glycol monomethyl ether+ethylacetate, ethylene glycol monomethyl ether+ethyl acetate, propyleneglycol monoethyl ether+ethyl acetate, ethylene glycol monoethylether+ethyl acetate, propylene glycol monopropyl ether+ethyl acetate,ethylene glycol monopropyl ether+ethyl acetate, methanol+methyl isobutylketone (MIK), ethanol+MIK, 1-propanol+MIK, 2-propanol+MIK, propyleneglycol monomethyl ether+MIK, ethylene glycol monomethyl ether+MIK,propylene glycol monoethyl ether+MIK, ethylene glycol monoethylether+MIK, propylene glycol monopropyl ether+MIK, ethylene glycolmonopropyl ether+MIK, methanol+cyclopentyl methyl ether,ethanol+cyclopentyl methyl ether, 1-propanol+cyclopentyl methyl ether,2-propanol+cyclopentyl methyl ether, propylene glycol monomethylether+cyclopentyl methyl ether, ethylene glycol monomethylether+cyclopentyl methyl ether, propylene glycol monoethylether+cyclopentyl methyl ether, ethylene glycol monoethylether+cyclopentyl methyl ether, propylene glycol monopropylether+cyclopentyl methyl ether, ethylene glycol monopropylether+cyclopentyl methyl ether, methanol+propylene glycol methyl etheracetate (PGMEA), ethanol+PGMEA, 1-propanol+PGMEA, 2-propanol+PGMEA,propylene glycol monomethyl ether+PGMEA, ethylene glycol monomethylether+PGMEA, propylene glycol monoethyl ether+PGMEA, ethylene glycolmonoethyl ether+PGMEA, propylene glycol monopropyl ether+PGMEA, andethylene glycol monopropyl ether+PGMEA.

A mixing proportion of the water-soluble organic solvent and thesubstantially water-insoluble organic solvent may be determined asappropriate although it is a usual practice to use 0.1 to 1,000 parts,preferably 1 to 500 parts, and more preferably 2 to 100 parts by weightof the water-soluble organic solvent per 100 parts by weight of thesubstantially water-insoluble organic solvent.

Subsequent step is to wash with neutral water. The water used forwashing may be deionized water or ultrapure water. The amount of wateris 0.01 to 100 liters (L), preferably 0.05 to 50 L, more preferably 0.1to 5 L per liter of the silicon-containing compound solution. Thewashing step may be carried out by feeding both the liquids into acommon vessel, agitating the contents, allowing the mixture to stand andto separate into two layers, and removing the water layer. The number ofwashing steps may be one or more, although the repetition of more than10 washing steps does not achieve the effect corresponding to such anumber of steps. Preferably the number of washing steps is from 1 toabout 5.

A final solvent is added to the silicon-containing compound solutionfrom which the basic catalyst has been removed, for inducing solventexchange under a reduced pressure, yielding a silicon-containingcompound solution. The temperature for solvent exchange is preferably 0to 100° C., more preferably 10 to 90° C., even more preferably 15 to 80°C., although the temperature depends on the type of extraction solventto be removed. The reduced pressure is preferably atmospheric orsubatmospheric, more preferably equal to or less than 80 kPa in absolutepressure, and even more preferably equal to or less than 50 kPa inabsolute pressure, although the pressure varies with the type ofextraction solvent to be removed and the vacuum pump, condenser, andheating temperature.

The final solvent added to the silicon-containing compound solution ispreferably an alcoholic solvent, examples of which include monoalkylethers of ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, dipropylene glycol, butane diol and the like.Preferred examples include butane diol monomethyl ether, propyleneglycol monomethyl ether, ethylene glycol monomethyl ether, butane diolmonoethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, and ethylene glycol monopropyl ether.

In another exemplary reaction procedure, water or a water-containingorganic solvent is added to the monomer or an organic solvent solutionof the monomer to start hydrolytic reaction. At this point, the catalystmay be added to the monomer or an organic solvent solution of themonomer, or water or a water-containing organic solvent. The reactiontemperature is 0 to 100° C., preferably 10 to 80° C. In the preferredprocedure, water is added dropwise at a temperature of 10 to 50° C.,after which the reaction mixture is matured at 20 to 80° C.

Of the organic solvents, if used, water-soluble solvents are preferred.Suitable organic solvents include methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone,tetrahydrofuran, acetonitrile, and polyhydric alcohol condensationderivatives such as propylene glycol monomethyl ether, ethylene glycolmonomethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, propylene glycol monopropyl ether, ethylene glycolmonopropyl ether, propylene glycol dimethyl ether, diethylene glycoldimethyl ether, propylene glycol monomethyl ether acetate, propyleneglycol monoethyl ether acetate, and propylene glycol monopropyl ether,and mixtures thereof.

The amount of the organic solvent used may be the same as describedabove for the one procedure. The resulting reaction mixture ispost-treated as described above for the one procedure, yielding asilicon-containing compound (E).

The molecular weight of the resulting silicon-containing compound (E)may be adjusted by a choice of monomer(s) and by control of reactionconditions during polymerization. Compounds having a weight averagemolecular weight in excess of 1,000,000 may produce foreign matter orcoating specks in some cases. Then the silicon-containing compoundpreferably has a weight average molecular weight equal to or less than800,000, more preferably 200 to 500,000, and even more preferably 300 to300,000. It is noted that the weight average molecular weight isdetermined by GPC using an RI detector or light scattering detector andpolystyrene standards.

In the metal oxide-containing film-forming composition of the invention,the silicon-containing compound (E) may be compounded in any amountrelative to component (A). Preferably they are combined such that theweight of component (A) is greater than the weight of component (E),i.e., (A)>(E).

To the inventive composition, water may be added. The addition of watercauses the metal oxide-containing compound to be hydrated, amelioratingthe lithography performance. The content of water is preferably frommore than 0% to less than 50%, more preferably from 0.3% to 30%, evenmore preferably 0.5% to 20% by weight, based on the solvent component inthe composition. Too high a water content may adversely affect theuniformity of a coated film and at the worst, cause cissing whereas toolow a water content may undesirably detract from lithographyperformance.

The total amount of solvents including water is preferably 500 to100,000 parts, more preferably 400 to 50,000 parts by weight per 100parts by weight of the base polymer (A).

Others

In the composition, a photoacid generator may be used. Examples of thephotoacid generator which can be used herein include:

-   (i) onium salts of the formula (P1a-1), (P1a-2) or (P1b),-   (ii) diazomethane derivatives of the formula (P2),-   (iii) glyoxime derivatives of the formula (P3),-   (iv) bissulfone derivatives of the formula (P4),-   (v) sulfonic acid esters of N-hydroxyimide compounds of the formula    (P5),-   (vi) β-ketosulfonic acid derivatives,-   (vii) disulfone derivatives,-   (viii) nitrobenzylsulfonate derivatives, and-   (ix) sulfonate derivatives.

These photoacid generators are described in detail.

(i) Onium Salts of Formula (P1a-1), (P1a-2) or (P1b):

Herein, R^(101a), R^(101b), and R^(101c) independently representstraight, branched or cyclic alkyl, alkenyl, oxoalkyl or oxoalkenylgroups of 1 to 12 carbon atoms, aryl groups of 6 to 20 carbon atoms, oraralkyl or aryloxoalkyl groups of 7 to 12 carbon atoms, wherein some orall hydrogen atoms may be replaced by alkoxy or other groups. Also,R^(101b) and R^(101c), taken together, may form a ring with the sulfuratom to which they are attached. R^(101b) and R^(101c) each are C₁-C₆alkylene groups when they form a ring. K⁻ is a non-nucleophilic counterion.

R^(101a), R^(101b), and R^(101c) may be the same or different and areillustrated below. Exemplary alkyl groups include methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl,4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl.Exemplary alkenyl groups include vinyl, allyl, propenyl, butenyl,hexenyl, and cyclohexenyl. Exemplary oxoalkyl groups include2-oxocyclopentyl and 2-oxocyclohexyl as well as 2-oxopropyl,2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, and2-(4-methylcyclohexyl)-2-oxoethyl. Exemplary aryl groups include phenyland naphthyl; alkoxyphenyl groups such as p-methoxyphenyl,m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl, p-tert-butoxyphenyl, andm-tert-butoxyphenyl; alkylphenyl groups such as 2-methylphenyl,3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl,4-butylphenyl, and dimethylphenyl; alkylnaphthyl groups such asmethylnaphthyl and ethylnaphthyl; alkoxynaphthyl groups such asmethoxynaphthyl and ethoxynaphthyl; dialkylnaphthyl groups such asdimethylnaphthyl and diethylnaphthyl; and dialkoxynaphthyl groups suchas dimethoxynaphthyl and diethoxynaphthyl. Exemplary aralkyl groupsinclude benzyl, phenylethyl, and phenethyl. Exemplary aryloxoalkylgroups are 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. Examples ofthe non-nucleophilic counter ion represented by K⁻ include halide ionssuch as chloride and bromide ions, fluoroalkylsulfonate ions such astriflate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate,arylsulfonate ions such as tosylate, benzenesulfonate,4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate, andalkylsulfonate ions such as mesylate and butanesulfonate.

Herein, R^(102a) and R^(102b) independently represent straight, branchedor cyclic alkyl groups of 1 to 8 carbon atoms. R¹⁰³ represents astraight, branched or cyclic alkylene group of 1 to 10 carbon atoms.R^(104a) and R^(104b) independently represent 2-oxoalkyl groups of 3 to7 carbon atoms. K⁻ is a non-nucleophilic counter ion.

Illustrative of the groups represented by R^(102a) and R^(102b) aremethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,cyclopropylmethyl, 4-methylcyclohexyl, and cyclohexylmethyl.Illustrative of the groups represented by R¹⁰³ are methylene, ethylene,propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene,1,4-cyclohexylene, 1,2-cyclohexylene, 1,3-cyclopentylene,1,4-cyclooctylene, and 1,4-cyclohexanedimethylene. Illustrative of thegroups represented by R^(104a) and R^(104b) are 2-oxopropyl,2-oxocyclopentyl, 2-oxocyclohexyl, and 2-oxocycloheptyl. Illustrativeexamples of the counter ion represented by K⁻ are the same asexemplified for formulae (P1a-1), (P1a-2) and (P1a-3).

(ii) Diazomethane Derivatives of Formula (P2)

Herein, R¹⁰⁵ and R¹⁰⁶ independently represent straight, branched orcyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms,substituted or unsubstituted aryl or halogenated aryl groups of 6 to 20carbon atoms, or aralkyl groups of 7 to 12 carbon atoms.

Of the groups represented by R¹⁰⁵ and R¹⁰⁶, exemplary alkyl groupsinclude methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, pentyl, hexyl, heptyl, octyl, amyl, cyclopentyl, cyclohexyl,cycloheptyl, norbornyl, and adamantyl. Exemplary halogenated alkylgroups include trifluoromethyl, 1,1,1-trifluoroethyl,1,1,1-trichloroethyl, and nonafluorobutyl. Exemplary aryl groups includephenyl; alkoxyphenyl groups such as p-methoxyphenyl, m-methoxyphenyl,o-methoxyphenyl, ethoxyphenyl, p-tert-butoxyphenyl, andm-tert-butoxyphenyl; and alkylphenyl groups such as 2-methylphenyl,3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl,4-butylphenyl, and dimethylphenyl. Exemplary halogenated aryl groupsinclude fluorophenyl, chlorophenyl, and 1,2,3,4,5-pentafluorophenyl.Exemplary aralkyl groups include benzyl and phenethyl.

(iii) Glyoxime Derivatives of Formula (P3)

Herein, R¹⁰⁷, R¹⁰⁸, and R¹⁰⁹ independently represent straight, branchedor cyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms,aryl or halogenated aryl groups of 6 to 20 carbon atoms, or aralkylgroups of 7 to 12 carbon atoms. Also, R¹⁰⁸ and R¹⁰⁹, taken together, mayform a ring with the carbon atom to which they are attached. R¹⁰⁸ andR¹⁰⁹ each are straight or branched C₁-C₆ alkylene groups when they forma ring.

Illustrative examples of the alkyl, halogenated alkyl, aryl, halogenatedaryl, and aralkyl groups represented by R¹⁰⁷, R¹⁰⁸, and R¹⁰⁹ are thesame as exemplified for R¹⁰⁵ and R¹⁰⁶. Examples of the alkylene groupsrepresented by R¹⁰⁸ and R¹⁰⁹ include methylene, ethylene, propylene,butylene, and hexylene.

(iv) Bissulfone Derivatives of Formula (P4)

Herein, R^(101a) and R^(101b) are as defined above (v) Sulfonic acidesters of N-hydroxyimide compounds of formula (P5)

Herein, R¹¹⁰ is a C₆-C₁₀ arylene group, C₁-C₆ alkylene group, or C₂-C₆alkenylene group wherein some or all hydrogen atoms may be replaced bystraight or branched C₁-C₄ alkyl or alkoxy groups, nitro, acetyl, orphenyl groups. R¹¹¹ is a straight, branched or cyclic alkyl group of 1to 8 carbon atoms, alkenyl, alkoxyalkyl, phenyl or naphthyl groupwherein some or all hydrogen atoms may be replaced by C₁-C₄ alkyl oralkoxy groups, phenyl groups (which may have substituted thereon a C₁-C₄alkyl or alkoxy, nitro, or acetyl group), hetero-aromatic groups of 3 to5 carbon atoms, or chlorine or fluorine atoms.

Of the groups represented by R¹¹⁰, exemplary arylene groups include1,2-phenylene and 1,8-naphthylene; exemplary alkylene groups includemethylene, ethylene, trimethylene, tetramethylene, phenylethylene, andnorbornane-2,3-diyl; and exemplary alkenylene groups include1,2-vinylene, 1-phenyl-1,2-vinylene, and 5-norbornene-2,3-diyl. Of thegroups represented by R¹¹¹, exemplary alkyl groups are as exemplifiedfor R^(101a) to R^(101c); exemplary alkenyl groups include vinyl,1-propenyl, allyl, 1-butenyl, 3-butenyl, isoprenyl, 1-pentenyl,3-pentenyl, 4-pentenyl, dimethylallyl, 1-hexenyl, 3-hexenyl, 5-hexenyl,1-heptenyl, 3-heptenyl, 6-heptenyl, and 7-octenyl; and exemplaryalkoxyalkyl groups include methoxymethyl, ethoxymethyl, propoxymethyl,butoxymethyl, pentyloxymethyl, hexyloxymethyl, heptyloxymethyl,methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl, pentyloxyethyl,hexyloxyethyl, methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl,methoxybutyl, ethoxybutyl, propoxybutyl, methoxypentyl, ethoxypentyl,methoxyhexyl, and methoxyheptyl.

Of the substituents on these groups, the C₁-C₄ alkyl groups includemethyl, ethyl, propyl, isopropyl, n-butyl, isobutyl and tert-butyl; andthe C₁-C₄ alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy,n-butoxy, isobutoxy, and tert-butoxy. The phenyl groups which may havesubstituted thereon an C₁-C₄ alkyl or alkoxy, nitro, or acetyl groupinclude phenyl, tolyl, p-tert-butoxyphenyl, p-acetylphenyl andp-nitrophenyl. The hetero-aromatic groups of 3 to 5 carbon atoms includepyridyl and furyl.

Illustrative examples of the photoacid generator include:

onium salts such as diphenyliodonium trifluoromethane-sulfonate,

-   (p-tert-butoxyphenyl)phenyliodonium trifluoromethanesulfonate,    diphenyliodonium p-toluenesulfonate,-   (p-tert-butoxyphenyl)phenyliodonium p-toluenesulfonate,    triphenylsulfonium trifluoromethanesulfonate,-   (p-tert-butoxyphenyl)diphenylsulfonium trifluoromethane-sulfonate,-   bis(p-tert-butoxyphenyl)phenylsulfonium trifluoromethane-sulfonate,-   tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,    triphenylsulfonium p-toluenesulfonate,-   (p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,-   bis(p-tert-butoxyphenyl)phenylsulfonium p-toluenesulfonate,-   tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,-   triphenylsulfonium nonafluorobutanesulfonate,-   triphenylsulfonium butanesulfonate,-   trimethylsulfonium trifluoromethanesulfonate,-   trimethylsulfonium p-toluenesulfonate,-   cyclohexylmethyl(2-oxocyclohexyl)sulfonium    trifluoromethane-sulfonate,-   cyclohexylmethyl(2-oxocyclohexyl)sulfonium p-toluenesulfonate,-   dimethylphenylsulfonium trifluoromethanesulfonate,-   dimethylphenylsulfonium p-toluenesulfonate,-   dicyclohexylphenylsulfonium trifluoromethanesulfonate,-   dicyclohexylphenylsulfonium p-toluenesulfonate,-   trinaphthylsulfonium trifluoromethanesulfonate,-   cyclohexylmethyl(2-oxocyclohexyl)sulfonium    trifluoromethane-sulfonate,-   (2-norbornyl)methyl(2-oxocyclohexyl)sulfonium    trifluoro-methanesulfonate,-   ethylenebis[methyl(2-oxocyclopentyl)sulfonium    trifluoro-methanesulfonate], and-   1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate;

diazomethane derivatives such as

-   bis(benzenesulfonyl)diazomethane,-   bis(p-toluenesulfonyl)diazomethane,-   bis(xylenesulfonyl)diazomethane,-   bis(cyclohexylsulfonyl)diazomethane,-   bis(cyclopentylsulfonyl)diazomethane,-   bis(n-butylsulfonyl)diazomethane,-   bis(isobutylsulfonyl)diazomethane,-   bis(sec-butylsulfonyl)diazomethane,-   bis(n-propylsulfonyl)diazomethane,-   bis(isopropylsulfonyl)diazomethane,-   bis(tert-butylsulfonyl)diazomethane,-   bis(n-amylsulfonyl)diazomethane,-   bis(isoamylsulfonyl)diazomethane,-   bis(sec-amylsulfonyl)diazomethane,-   bis(tert-amylsulfonyl)diazomethane,-   1-cyclohexylsulfonyl-1-(tert-butylsulfonyl)diazomethane,-   1-cyclohexylsulfonyl-1-(tert-amylsulfonyl)diazomethane, and-   1-tert-amylsulfonyl-1-(tert-butylsulfonyl)diazomethane;

glyoxime derivatives such as

-   bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime,-   bis-O-(p-toluenesulfonyl)-α-diphenylglyoxime,-   bis-O-(p-toluenesulfonyl)-α-dicyclohexylglyoxime,-   bis-O-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,-   bis-O-(p-toluenesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,-   bis-O-(n-butanesulfonyl)-α-dimethylglyoxime,-   bis-O-(n-butanesulfonyl)-α-diphenylglyoxime,-   bis-O-(n-butanesulfonyl)-α-dicyclohexylglyoxime,-   bis-O-(n-butanesulfonyl)-2,3-pentanedioneglyoxime,-   bis-O-(n-butanesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,-   bis-O-(methanesulfonyl)-α-dimethylglyoxime,-   bis-O-(trifluoromethanesulfonyl)-α-dimethylglyoxime,-   bis-O-(1,1,1-trifluoroethanesulfonyl)-α-dimethylglyoxime,-   bis-O-(tert-butanesulfonyl)-α-dimethylglyoxime,-   bis-O-(perfluorooctanesulfonyl)-α-dimethylglyoxime,-   bis-O-(cyclohexanesulfonyl)-α-dimethylglyoxime,-   bis-O-(benzenesulfonyl)-α-dimethylglyoxime,-   bis-O-(p-fluorobenzenesulfonyl)-α-dimethylglyoxime,-   bis-O-(p-tert-butylbenzenesulfonyl)-α-dimethylglyoxime,-   bis-O-(xylenesulfonyl)-α-dimethylglyoxime, and-   bis-O-(camphorsulfonyl)-α-dimethylglyoxime;

bissulfone derivatives such as

-   bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane,    bismethylsulfonylmethane, bisethylsulfonylmethane,    bispropylsulfonylmethane, bisisopropylsulfonylmethane,    bis-p-toluenesulfonylmethane, and bisbenzenesulfonylmethane;

β-ketosulfonic acid derivatives such as2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane and2-isopropylcarbonyl-2-(p-toluenesulfonyl)propane;

disulfone derivatives such as diphenyl disulfone and dicyclohexyldisulfone;

nitrobenzyl sulfonate derivatives such as 2,6-dinitrobenzylp-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate;

sulfonic acid ester derivatives such as1,2.3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and1,2,3-tris(p-toluenesulfonyloxy)benzene; and

sulfonic acid esters of N-hydroxyimides such as

-   N-hydroxysuccinimide methanesulfonate,-   N-hydroxysuccinimide trifluoromethanesulfonate,-   N-hydroxysuccinimide ethanesulfonate,-   N-hydroxysuccinimide 1-propanesulfonate,-   N-hydroxysuccinimide 2-propanesulfonate,-   N-hydroxysuccinimide 1-pentanesulfonate,-   N-hydroxysuccinimide 1-octanesulfonate,-   N-hydroxysuccinimide p-toluenesulfonate,-   N-hydroxysuccinimide p-methoxybenzenesulfonate,-   N-hydroxysuccinimide 2-chloroethanesulfonate,-   N-hydroxysuccinimide benzenesulfonate,-   N-hydroxysuccinimide 2,4,6-trimethylbenzenesulfonate,-   N-hydroxysuccinimide 1-naphthalenesulfonate,-   N-hydroxysuccinimide 2-naphthalenesulfonate,-   N-hydroxy-2-phenylsuccinimide methanesulfonate,-   N-hydroxymaleimide methanesulfonate,-   N-hydroxymaleimide ethanesulfonate,-   N-hydroxy-2-phenylmaleimide methanesulfonate,-   N-hydroxyglutarimide methanesulfonate,-   N-hydroxyglutarimide benzenesulfonate,-   N-hydroxyphthalimide methanesulfonate,-   N-hydroxyphthalimide benzenesulfonate,-   N-hydroxyphthalimide trifluoromethanesulfonate,-   N-hydroxyphthalimide p-toluenesulfonate,-   N-hydroxynaphthalimide methanesulfonate,-   N-hydroxynaphthalimide benzenesulfonate,-   N-hydroxy-5-norbornene-2,3-dicarboxyimide methanesulfonate,-   N-hydroxy-5-norbornene-2,3-dicarboxyimide    trifluoromethane-sulfonate, and-   N-hydroxy-5-norbornene-2,3-dicarboxyimide p-toluenesulfonate.

Preferred among these photoacid generators are onium salts such astriphenylsulfonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethane-sulfonate,tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane-sulfonate,(2-norbornyl)methyl(2-oxocylohexyl)sulfonium trifluoro-ethanesulfonate,and 1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate;diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane,bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane,bis(sec-butylsulfonyl)diazomethane, bis(n-propylsulfonyl)diazomethane,bis(isopropylsulfonyl)diazomethane, andbis(tert-butylsulfonyl)diazomethane; glyoxime derivatives such asbis-O-(p-toluenesulfonyl)-α-dimethylglyoxime andbis-O-(n-butanesulfonyl)-α-dimethylglyoxime; bissulfone derivatives suchas bisnaphthylsulfonylmethane; and sulfonic acid esters ofN-hydroxyimide compounds such as N-hydroxysuccinimide methanesulfonate,N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide1-propanesulfonate, N-hydroxysuccinimide 2-propanesulfonate,N-hydroxysuccinimide 1-pentanesulfonate, N-hydroxysuccinimidep-toluenesulfonate, N-hydroxynaphthalimide methanesulfonate, andN-hydroxynaphthalimide benzenesulfonate.

These photoacid generators may be used singly or in combinations of twoor more thereof. An appropriate amount of the photoacid generator addedis 0.01 to 50 parts, and more preferably 0.05 to 40 parts by weight, per100 parts by weight of the base polymer (A).

In a preferred embodiment, a mono or polyhydric alcohol substituted witha cyclic ether may be added as a stabilizer to the metaloxide-containing film-forming composition so that the composition isfurther improved in stability. Specifically suitable alcohols includeether compounds having the structure shown below.

Herein R^(90a) is hydrogen, a straight, branched or cyclic monovalenthydrocarbon group of 1 to 10 carbon atoms,R⁹¹O—CH₂CH₂O)_(n1)—(CH₂)_(n2)— (wherein R⁹¹ is hydrogen or methyl,0≦n1≦5, 0≦n2≦3), or R⁹²O—[CH(CH₃)CH₂O]_(n3)—(CH₂)n₄— (wherein R⁹² ishydrogen or methyl, 0≦n3≦5, 0≦n4≦3). R^(90b) is hydroxyl, a straight,branched or cyclic monovalent hydrocarbon group of 1 to 10 carbon atomshaving at least one hydroxyl group, HO—(CH₂CH₂O)_(n5)—(CH₂)_(n6)—(wherein 1≦n5≦5, 1≦n6≦3), or HO—[CH(CH₃)CH₂O]_(n7)—(CH₂)_(n8)— (wherein1≦n7≦5, 1≦n8≦3).

The stabilizer may be used alone or in admixture. An appropriate amountof the stabilizer added is 0.001 to 50 parts, and preferably 0.01 to 40parts by weight per 100 parts by weight of the base polymer (A).Stabilizers of the preferred structure include crown ether derivativesand compounds substituted with a bicyclo ring having an oxygen atom atthe bridgehead. The addition of such a stabilizer helps to keep theelectric charge of acid more stable, contributing to furtherstabilization of the metal oxide-containing compounds in thecomposition.

In the composition, a surfactant may optionally be compounded. Thepreferred surfactants are nonionic surfactants, for example,perfluoroalkyl polyoxyethylene ethanols, fluorinated alkyl esters,perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, andfluorinated organosiloxanes. They are commercially available, forexample, under the trade name of Fluorad FC-430, FC-431 and FC-4430(Sumitomo 3M Co., Ltd.), Surflon S-141, S-145, KH-10, KH-20, KH-30 andKH-40 (Asahi Glass Co., Ltd.), Unidyne DS-401, DS-403 and DS-451 (DaikinIndustries Ltd.), Megaface F-8151 (Dai-Nippon Ink & Chemicals, Inc.),X-70-092 and X-70-093 (Shin-Etsu Chemical Co., Ltd.). Inter alia,Fluorad FC-4430, KH-20, KH-30, and X-70-093 are preferred.

The surfactant is added to the composition in an ordinary amount as longas the objects of the invention are not compromised, preferably in anamount of 0 to 10 parts, more preferably 0 to 5 parts by weight, per 100parts by weight of the base polymer (A).

A metal oxide-containing film useful as an etching mask can be formed ona substrate from the metal oxide-containing film forming composition ofthe invention by spin coating or similar techniques, as is thephotoresist film. After spin coating, the coating is desirably baked toevaporate off the solvent and to promote crosslinking reaction forpreventing the coating from mixing with the overlying resist film. Thebaking step is preferably effected at a temperature of 50 to 500° C. fora time of 10 to 300 seconds. While the preferred temperature rangevaries depending on the structure of a device to be manufactured, it istypically equal to or lower than 400° C. in order to minimize thermaldamage to the device.

According to the invention, a pattern can be formed by forming a metaloxide-containing film, as described above, on a processable portion of aprocessable substrate via an intervening undercoat film, and forming aphotoresist film on the metal oxide-containing film. The processableportion of a processable substrate may be a low-dielectric constantinsulating film having a k value of up to 3, a primarily processedlow-dielectric constant insulating film, a nitrogen and/oroxygen-containing inorganic film, a metal film or the like. Theundercoat layer is preferably an organic film. The resist compositionfrom which the photoresist film is formed is preferably a silicon-free,chemically amplified resist composition.

More specifically, the processable substrate (i.e., substrate to beprocessed or patterned) may be a processable layer or portion formed ona base substrate. The base substrate is not particularly limited and maybe made of any material which is selected from Si, amorphous silicon(α-Si), polycrystalline silicon (p-Si), SiO₂, SiN, SiON, W, TiN, Al,etc, but different from the processable layer. The processable layer maybe any of films of Si, SiO₂, SiN, SiON, p-Si, α-Si, W, W—Si, Al, Cu,Al—Si, etc., and various low dielectric films and etching stop filmsthereof and generally has a thickness of 50 to 10,000 nm, preferably 100to 5,000 nm.

In a further embodiment, an antireflective coating (ARC) may be formedbetween the metal oxide-containing film and the overcoat resist filmusing a commercially available ARC material. Usually the ARC is formedof a compound having an aromatic substituent group. The ARC must beselected so as to impose little or no etching load to the overcoatresist film when the pattern of the overcoat resist film is transferredby dry etching. For example, if the thickness of the ARC is equal to orless than 80%, preferably equal to or less than 50% of the thickness ofthe overcoat resist film, the load applied during dry etching isminimized. In this embodiment, the ARC is preferably adjusted to aminimum reflectance equal to or less than 2%, more preferably equal toor less than 1%, and even more preferably equal to or less than 0.5%.

When the metal oxide-containing film of the invention is used in theexposure process using ArF excimer laser radiation, the overcoat resistfilm may be any of ordinary ArF excimer laser lithography resistcompositions. There are known a number of candidates for the ArF excimerlaser lithography resist composition, including resist compositions ofthe positive working type primarily comprising a polymer which becomessoluble in an alkaline aqueous solution as a result of decomposition ofacid labile groups under the action of an acid, a photoacid generator,and a basic compound for controlling acid diffusion; and resistcompositions of the negative working type primarily comprising a polymerwhich becomes insoluble in an alkaline aqueous solution as a result ofreaction with a crosslinker under the action of an acid, a photoacidgenerator, a crosslinker, and a basic compound for controlling aciddiffusion. Properties of a resist composition differ depending on whattype of polymer is used. Well-known polymers are generally classifiedinto poly(meth)acrylic, cycloolefin/maleic anhydride (COMA) copolymer,COMA-(meth)acrylic hybrid, ring-opening metathesis polymerization(ROMP), and polynorbornene systems. Of these, a resist compositioncomprising a poly(meth)acrylic polymer has superior resolution to otherpolymers because etching resistance is achieved by introducing analicyclic skeleton into side chain.

There are known a number of ArF excimer laser lithography resistcompositions comprising poly(meth)acrylic polymers. For the positivetype, a polymer is composed of a combination of units for providing themain function of etching resistance, units which turn to be alkalisoluble as a result of decomposition under the action of an acid, andunits for providing adhesion, or in some cases, a combination comprisingone unit capable of providing two or more of the above-mentionedfunctions. As the unit which changes alkali solubility under the actionof an acid, (meth)acrylic acid esters having an acid labile group withan adamantane skeleton (see JP-A 9-73173) and (meth)acrylic acid estershaving an acid labile group with a norbornane or tetracyclododecaneskeleton (see JP-A 2003-84438) are advantageously used because theyprovide high resolution and etching resistance. As the unit whichensures adhesion, (meth)acrylic acid esters having a norbornane sidechain with a lactone ring (see WO 00/01684), (meth)acrylic acid estershaving an oxanorbornane side chain (see JP-A 2000-159758), and(meth)acrylic acid esters having a hydroxyadamantyl side chain (see JP-A8-12626) are advantageously used because they provide satisfactoryetching resistance and high resolution. Further, a polymer comprisingunits having as a functional group an alcohol which exhibits acidity byfluorine substitution on the vicinal carbon (see Polym. Mater. Sci.Eng., 1997, 77, pp 449) draws attention as a resist polymer complyingwith the immersion lithography of the current great interest because theunits impart anti-swelling physical properties and hence, highresolution to the polymer. However, a decline of etching resistance dueto inclusion of fluorine within the polymer is a problem. The metaloxide-containing film (for etching mask) of the invention isadvantageously used in combination with such an organic resist materialwhich is relatively difficult to secure etching resistance.

After the metal oxide-containing film (for etching mask) is formed, aphotoresist layer is formed thereon using a photoresist compositionsolution. Like the metal oxide-containing film (for etching mask), thephotoresist composition solution is preferably applied by spin coating.Once the resist composition is spin coated, it is prebaked, preferablyat 80 to 180° C. for 10 to 300 seconds. The coating is then exposed,followed by post-exposure bake (PEB) and development, yielding a resistpattern.

The metal oxide-containing film (for etching mask) is typically etchedwith fluorine-based gases such as fluorocarbon gases or the like. Withthese gases, the metal oxide-containing film (for etching mask) isetched at so high an etching rate that the overcoat resist filmundergoes less slimming.

In the multilayer resist process using the metal oxide-containing filmof the invention, an undercoat film is provided between the metaloxide-containing film and the processable substrate. When the undercoatfilm is used as an etching mask for the processable substrate, theundercoat film is preferably an organic film having an aromaticframework. When the undercoat film is a sacrificial film, it may beeither an organic film or a silicon-containing material having a siliconcontent equal to or less than 15% by weight.

In the multilayer resist process using as the undercoat film an organicfilm which can serve as an etching mask for the processable substrate,the organic film is used in another process involving transferring theresist pattern resulting from previous pattern formation to the metaloxide-containing film and transferring again the pattern of metaloxide-containing film to the organic film, and specifically, in thesecond transfer step. Then the organic film should have suchcharacteristics that it can be etch processed under the etchingconditions to which the metal oxide-containing film is highly resistant,but it is highly resistant to the etching conditions under which theprocessable substrate is etch processed.

With respect to the organic film as the undercoat film, there are knowna number of films including undercoat films for the tri-layer resistprocess and undercoat films for the bi-layer resist process usingsilicon resist compositions. A number of resins including4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resin with a molecularweight of 11,000 as described in JP-A 2005-128509 and other novolacresins are known as the resist undercoat film material for the bi- ortrilayer resist process, and any of them can be used herein. If it isdesired to enhance heat resistance beyond ordinary novolac resins, it ispossible to incorporate polycyclic skeletons as in4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resins or to selectpolyimide resins (e.g., JP-A 2004-153125).

The organic film can be formed on a substrate from a compositionsolution by spin coating or similar techniques like the photoresistcomposition. After the resist undercoat film is formed by spin coatingor the like, it is desirably baked to evaporate off the organic solvent.The baking is preferably effected at a temperature of 80 to 300° C. fora time of 10 to 300 seconds.

Although the thickness of each film is not particularly limited andvaries depending on etching conditions, the undercoat film preferablyhas a thickness of at least 10 nm, and more preferably from 50 nm to50,000 nm, the metal oxide-containing film preferably has a thicknessfrom 1 nm to 200 nm, and the photoresist film preferably has a thicknessfrom 1 nm to 300 nm.

The tri-layer resist process using the metal oxide-containing film (foretching mask) according to the invention is described below. In theprocess, an organic film is first formed on a processable substrate byspin coating or similar techniques. This organic film is desired to havehigh etching resistance since it will serve as a mask during lateretching of the processable substrate, and is also desired to becrosslinked by heat or acid after spin coating since it should beprevented from intermixing with an overlying metal oxide-containing film(for etching mask). On the organic film, a metal oxide-containing film(for etching mask) of the inventive composition and a photoresist filmare formed by the above-described technique. In accordance with thestandard procedure, the resist film is imagewise exposed to a lightsource selected for a particular resist film, for example, KrF excimerlaser, ArF excimer laser or F₂ laser, heat treated under conditionsselected for a particular resist film, and developed with a liquiddeveloper, obtaining a resist pattern. While the resist pattern is madean etching mask, etching is carried out under dry etching conditionsunder which the etching rate of the metal oxide-containing film isdominantly high relative to the organic film, for example, dry etchingwith a fluorine gas plasma. When the ARC and the metal oxide-containingfilm are etch processed in this way, a pattern of the metaloxide-containing film is obtained without the substantial influence ofpattern changes by side etching of the resist film. Then, the undercoatorganic film is etched under dry etching conditions under which theetching rate of the undercoat organic film is dominantly high relativeto the substrate (having the metal oxide-containing film pattern towhich the resist pattern has been transferred as described above), forexample, by reactive dry etching with an oxygen-containing gas plasma orreactive dry etching with a hydrogen/nitrogen-containing gas plasma.This etching step produces a pattern of the undercoat organic film whilethe resist layer as the uppermost layer is often lost at the same time.Further, while the thus patterned undercoat organic film is made anetching mask, the processable substrate is processed by dry etching, forexample, fluorine dry etching or chlorine dry etching. The processablesubstrate can be etch processed at a high accuracy.

EXAMPLE

Synthesis Examples and Examples are given below together withComparative Examples for further illustrating the invention although theinvention is not limited thereby. All percents are by weight. Themolecular weight (Mw) is determined by gel permeation chromatography(GPC) versus polystyrene standards.

Synthesis of Metal Oxide-Containing Compounds Synthesis Example 1

A mixture of 10 g of phenyltrimethoxysilane, 20 g of2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 10 g of germaniumtetrabutoxide, and 35 g of propylene glycol methyl ether was added to amixture of 40 g of propylene glycol methyl ether, 1 g of methanesulfonicacid, and 50 g of deionized water. The mixture was held at 40° C. for 12hours while hydrolytic condensation took place. Then the by-productalcohol was distilled off under a reduced pressure. To the reactionmixture, 800 ml of ethyl acetate and 300 ml of propylene glycol methylether were added. The water layer was separated off. To the remainingorganic layer, 100 ml of deionized water was added, followed byagitation, static holding and separation. This operation was repeatedthree times. To the remaining organic layer, 200 ml of propylene glycolmethyl ether was added. Concentration under a reduced pressure yielded100 g of a propylene glycol methyl ether solution of metaloxide-containing compound #1 (polymer concentration 20%). The solutionwas analyzed for methanesulfonate ions by ion chromatography, but noions were detected. The product had a Mw of 3,000.

Synthesis Example 2

A mixture of 10 g of phenyltrimethoxysilane, 20 g of2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 10 g of titaniumtetrabutoxide, 20 g of 2,4-pentanedione, and 35 g of propylene glycolmethyl ether was added to a mixture of 40 g of propylene glycol methylether, 1 g of methanesulfonic acid, and 50 g of deionized water. Themixture was held at 30° C. for 12 hours while hydrolytic condensationtook place. Then the by-product alcohol was distilled off under areduced pressure. To the remaining solution, 200 ml of propylene glycolmethyl ether was added. Further concentration under a reduced pressureyielded 120 g of a propylene glycol methyl ether solution of metaloxide-containing compound #2 (polymer concentration 20%). The producthad a Mw of 8,000.

Synthesis Example 3

A mixture of 10 g of phenyltrimethoxysilane, 20 g of2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 10 g of hafniumtetrapropoxide, and 35 g of propylene glycol ethyl ether was added to amixture of 40 g of propylene glycol ethyl ether, 1 g of hydrochloricacid, and 50 g of deionized water. The mixture was held at 10° C. for 12hours while hydrolytic condensation took place. Then the by-productalcohol was distilled off under a reduced pressure. To the remainingsolution, 200 ml of propylene glycol ethyl ether was added. Furtherconcentration under a reduced pressure yielded 100 g of a propyleneglycol ethyl ether solution of metal oxide-containing compound #3(polymer concentration 20%). The product had a Mw of 5,000.

Synthesis Example 4

A mixture of 70 g of tetramethoxysilane, 25 g of methyltrimethoxysilane,25 g of a silane compound of formula (i), shown below, 10 g of aluminumtrimethoxide, and 10 g of phenyltrimethoxysilane was added to a mixtureof 1 g of 35% hydrochloric acid and 260 g of deionized water at roomtemperature. The mixture was held at room temperature for 8 hours whilehydrolytic condensation took place. Then the by-product methanol wasdistilled off under a reduced pressure. To the remaining solution, 800ml of ethyl acetate and 300 ml of propylene glycol propyl ether wereadded. The water layer was separated off. To the remaining organiclayer, 100 ml of deionized water was added, followed by agitation,static holding and separation. This operation was repeated three times.To the remaining organic layer, 200 ml of propylene glycol monopropylether was added. Concentration under a reduced pressure yielded 300 g ofa propylene glycol monopropyl ether solution of metal oxide-containingcompound #4 (polymer concentration 20%). The solution was analyzed forchloride ions by ion chromatography, but no ions were detected. Theproduct had a Mw of 2,500.

Synthesis Example 5

A mixture of 40 g of tetramethoxysilane, 10 g of methyltrimethoxysilane,50 g of trimethyl borate, and 10 g of phenyltrimethoxysilane was addedto a mixture of 200 g of ethanol, 100 g of deionized water, and 3 g ofmethanesulfonic acid at room temperature. The mixture was held at roomtemperature for 8 hours while hydrolytic condensation took place. Thenthe by-product methanol was distilled off under a reduced pressure. Tothe remaining solution, 800 ml of ethyl acetate and 300 ml of ethyleneglycol monopropyl ether were added. The water layer was separated off.To the remaining organic layer, 100 ml of deionized water was added,followed by agitation, static holding and separation. This operation wasrepeated three times. To the remaining organic layer, 200 ml of ethyleneglycol monopropyl ether was added. Concentration under a reducedpressure yielded 300 g of an ethylene glycol monopropyl ether solutionof metal oxide-containing compound #5 (polymer concentration 20%). Thesolution was analyzed for methanesulfonate ions by ion chromatography,finding that 99% of the catalyst used in reaction had been removed. Theproduct had a Mw of 2,100.

Synthesis Example 6

A mixture of 40 g of tetramethoxysilane, 10 g of methyltrimethoxysilane,20 g of 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, and 10 g ofphenyltrimethoxysilane was added to a mixture of 200 g of ethanol, 100 gof deionized water, and 3 g of methanesulfonic acid at room temperature.The mixture was held at room temperature for 8 hours while hydrolyticcondensation took place. Then the by-product methanol was distilled offunder a reduced pressure. To the remaining solution, 800 ml of ethylacetate and 300 ml of ethylene glycol monopropyl ether were added. Thewater layer was separated off. To the remaining organic layer, 100 ml ofdeionized water was added, followed by agitation, static holding andseparation. This operation was repeated three times. To the remainingorganic layer, 200 ml of ethylene glycol monopropyl ether was added.Concentration under a reduced pressure yielded 300 g of an ethyleneglycol monopropyl ether solution of metal oxide-containing compound #6(polymer concentration 20%). The solution was analyzed formethanesulfonate ions by ion chromatography, finding that 99% of thecatalyst used in reaction had been removed. The product had a Mw of3,500.

Synthesis of Silicon-Containing Compounds Synthesis Example 7

A 1,000-ml glass flask was charged with 500 g of ethanol, 250 g ofdeionized water, and 2.5 g of 25% tetramethylammonium hydroxide. Whilethe mixture was stirred at 55° C., a mixture of 97 g oftetraethoxysilane and 73 g of methyltrimethoxysilane was added dropwisethereto over 2 hours. The mixture was stirred for one hour at 55° C. andthen cooled to room temperature, after which 3 g of 20% maleic acidaqueous solution was added. To the solution, 1000 ml of propylene glycolmonopropyl ether was added. The solution was concentrated to 900 ml.Thereafter, 2,000 ml of ethyl acetate was added to the concentrate,which was washed twice with 300 ml of deionized water and allowed toseparate. The ethyl acetate layer was concentrated under reducedpressure, obtaining 900 g of a propylene glycol monopropyl ethersolution of silicon-containing compound #7 (polymer concentration 7%).The product had a Mw of about 100,000.

Synthesis Example 8

A 1,000-ml glass flask was charged with 260 g of deionized water and 5 gof 65% nitric acid. A mixture of 70 g of tetraethoxysilane, 70 g ofmethyltrimethoxysilane, and 10 g of phenyltrimethoxysilane was addedthereto at room temperature. The flask was held at room temperature for8 hours while hydrolytic condensation took place. Then methanol andby-product ethanol were distilled off under reduced pressure. To theremaining solution, 800 ml of ethyl acetate and 300 ml of propyleneglycol monopropyl ether were added. The water layer was separated off.To the remaining organic layer, 100 ml of 1% maleic acid aqueoussolution was added, followed by agitation, static holding andseparation. This operation was repeated two times. To the remainingorganic layer, 100 ml of deionized water was added, followed byagitation, static holding and separation. This operation was repeatedthree times. To the remaining organic layer, 200 ml of propylene glycolmonopropyl ether was added. Concentration under a reduced pressureyielded 300 g of a propylene glycol monopropyl ether solution ofsilicon-containing compound #8 (polymer concentration 21%). The producthad a molecular weight (Mw) of 2,000.

Examples and Comparative Examples

Metal oxide-containing film-forming composition solutions were preparedby dissolving metal oxide-containing compounds (#1 to #6),silicon-containing compounds (#7, #8), acid, thermal crosslinkaccelerator, and additive in a solvent according to the formulationshown in Table 1, and passing through a fluoroplastic filter having apore size of 0.1 μm. These solutions are designated Sol. 1 to 18.

TABLE 1 Metal oxide-containing film-forming composition Metal oxide-containing compound + Thermal Si-containing crosslink Water/ Othercompound accelerator Acid Solvent stabilizer additive Designation (pbw)(pbw) (pbw) (pbw) (pbw) (pbw) Example 1 Sol. 1 #1 (4.0) TPSOAc maleicpropylene glycol — — (0.04) acid methyl ether (0.04) (100) 2 Sol. 2 #1(4.0) TPSOH oxalic propylene glycol water (10) — (0.04) acid methylether (0.04) (100) 3 Sol. 3 #1 (4.0) TPSCl maleic propylene glycol water(10) TPSNf (0.04) acid methyl ether (0.02) TPSOAc (0.04) (100) (0.003) 4Sol. 4 #1 (4.0) TPSMA maleic propylene glycol water (10) — (0.04) acidmethyl ether Stabilizer 1 TMAOAc (0.04) (100) (5) (0.003) oxalic acid(0.04) 5 Sol. 5 #1 (4.0) TPSN maleic propylene glycol water (10) — #7(0.4) (0.04) acid methyl ether Stabilizer 1 (0.04) (100) (5) oxalic acid(0.04) 6 Sol. 6 #1 (4.0) TPSMA maleic propylene glycol Stabilizer 1 — #8(0.4) (0.04) acid methyl ether (5) (0.04) (100) 7 Sol. 7 #1 (3.2) TPSOAcfumaric propylene glycol Stabilizer 1 — #7 (0.4) (0.04) acid methylether (5) #8 (0.4) (0.04) (100) 8 Sol. 8 #2 (4.0) TPSOAc maleicpropylene glycol water (10) — (0.04) acid methyl ether Stabilizer 2(0.04) (100) (5) 9 Sol. 9 #2 (4.0) TPSMA meleic propylene glycol water(10) (0.04) acid methyl ether Stabilizer 2 (0.04) (100) (5) 10 Sol. 10#3 (4.0) TPSOAc maleic propylene glycol water (10) — (0.04) acid ethylether Stabilizer 2 (0.04) (100) (5) 11 Sol. 11 #3 (4.0) TPSOH maleicpropylene glycol water (10) — (0.04) acid ethyl ether Stabilizer 3(0.04) (100) (5) 12 Sol. 12 #4 (4.0) TPSMA maleic propylene glycol water(10) — (0.04) acid propyl ether Stabilizer 3 (0.04) (100) (5) 13 Sol. 13#4 (4.0) TPSOAc maleic propylene glycol water (10) — (0.04) acid propylether Stabilizer 4 (0.04) (100) (5) 14 Sol. 14 #5 (4.0) TPSMA maleicpropylene glycol water (10) — (0.04) acid propyl ether Stabilizer 4(0.04) (100) (5) 15 Sol. 15 #5 (4.0) TPSN maleic propylene glycol water(10) — (0.04) acid propyl ether Stabilizer 5 (0.04) (100) (5)Comparative Example 1 Sol. 16 #6 (4.0) TPSMA maleic propylene glycolwater (10) — (0.04) acid propyl ether Stabilizer 5 (0.04) (100) (5) 2Sol. 17 #1 (4.0) — maleic propylene glycol water (10) — acid propylether Stabilizer 5 (0.04) (100) (5) 3 Sol. 18 #1 (4.0) TPSMA — propyleneglycol water (10) — (0.04) propyl ether Stabilizer 5 (100) (5) TPSOAc:triphenylsulfonium acetate (photo-degradable thermal crosslinkaccelerator) TPSOH: triphenylsulfonium hydroxide (photo-degradablethermal crosslink accelerator) TPSCl: triphenylsulfonium chloride(photo-degradable thermal crosslink accelerator) TPSMA:mono(triphenylsulfonium) maleate (photo-degradable thermal crosslinkaccelerator) TPSN: triphenylsulfonium nitrate (photo-degradable thermalcrosslink accelerator) TMAOAc: tetramethylammonium acetate(non-photo-degradable thermal crosslink accelerator) TPSNf:triphenylsulfonium nonafluorobutanesulfonate (photoacid generator)Stabilizer 1:

Stabilizer 2:

Stabilizer 3:

Stabilizer 4:

Stabilizer 5:

First, an undercoat-forming material, specifically a compositioncontaining 28 parts by weight of a 4,4′-(9H-fluoren-9-ylidene)bisphenolnovolac resin with a molecular weight of 11,000 and 100 parts by weightof PGMEA solvent (see JP-A 2005-128509) was spin coated onto a siliconwafer and baked at 200° C. for 1 minute to form an undercoat organicfilm of 300 nm thick. While a number of resins including theabove-specified resin and other novolac resins are known as theundercoat organic film material for the multilayer resist process, anyof them can be used herein.

Next, each of the metal oxide-containing film forming solutions (Sol. 1to 18) was spin coated and baked at 200° C. for 1 minute to form a metaloxide-containing film of 100 nm thick.

Further, to form an overcoat resist film, a resist composition for ArFexcimer laser lithography (designated Resist 1) was prepared bydissolving 10 parts by weight of a resin, identified below, 0.2 part byweight of triphenylsulfonium nonafluorobutanesulfonate as a photoacidgenerator and 0.02 part by weight of triethanolamine as a basic compoundin propylene glycol monomethyl ether acetate (PGMEA) containing 0.1 wt %of Fluorad FC-430 (3M-Sumitomo Co., Ltd.) and passing through afluoroplastic filter having a pore size of 0.1 μm.

Resin:

(Me=methyl, Et=ethyl)

The resist composition was coated onto the metal oxide-containingintermediate film and baked at 130° C. for 60 seconds to form aphotoresist layer of 200 nm thick.

Thereafter, the resist layer was exposed using an ArF laser stepperS305B (Nikon Corporation, NA 0.68, σ 0.85, 2/3 annular illumination, Crmask), then baked (PEB) at 110° C. for 90 seconds, and developed with a2.38 wt % aqueous solution of tetramethylammonium hydroxide (TMAH),thereby giving a positive pattern. The profile of the 90 nmline-and-space pattern was observed, with the results shown in Table 2.

TABLE 2 Pattern profile Designation Pattern profile Example 1 Sol. 1good Example 2 Sol. 2 good Example 3 Sol. 3 good Example 4 Sol. 4 goodExample 5 Sol. 5 good Example 6 Sol. 6 good Example 7 Sol. 7 goodExample 8 Sol. 8 good Example 9 Sol. 9 good Example 10 Sol. 10 goodExample 11 Sol. 11 good Example 12 Sol. 12 good Example 13 Sol. 13 goodExample 14 Sol. 14 good Example 15 Sol. 15 good Comparative Example 1Sol. 16 good Comparative Example 2 Sol. 17 good Comparative Example 3Sol. 18 good

In all Examples, the patterns were found to be free ofsubstrate-proximate footing, undercut and intermixing phenomena.

Next, dry etching resistance was tested. Each of the metaloxide-containing film forming solutions (Sol. 1 to 18) was spin coatedand baked at 200° C. for 1 minute to form an metal oxide-containing filmof 100 nm thick (Films 1 to 18). An etching test was performed on thesefilms, the undercoat film, and the photoresist film under the followingset of etching conditions (1). The results are shown in Table 3.

(1) CHF₃/CF₄ Gas Etching Test

-   -   Instrument: dry etching instrument TE-8500P by Tokyo Electron        Ltd.    -   Chamber pressure: 40.0 Pa    -   RF power: 1,300 W    -   Gap: 9 mm    -   CHF₃ gas flow rate: 30 ml/min    -   CF₄ gas flow rate: 30 ml/min    -   Ar gas flow rate: 100 ml/min    -   Treating time: 10 sec

TABLE 3 Metal oxide- containing Metal oxide- CHF₃/CF₄ gas film-formingcontaining dry etching rate composition film (nm/min) Example 1 Sol. 1Film 1 450 Example 2 Sol. 2 Film 2 450 Example 3 Sol. 3 Film 3 450Example 4 Sol. 4 Film 4 450 Example 5 Sol. 5 Film 5 450 Example 6 Sol. 6Film 6 450 Example 7 Sol. 7 Film 7 450 Example 8 Sol. 8 Film 8 410Example 9 Sol. 9 Film 9 410 Example 10 Sol. 10 Film 10 420 Example 11Sol. 11 Film 11 420 Example 12 Sol. 12 Film 12 410 Example 13 Sol. 13Film 13 410 Example 14 Sol. 14 Film 14 420 Example 15 Sol. 15 Film 15420 Comparative Example 1 Sol. 16 Film 16 200 Comparative Example 2 Sol.17 Film 17 450 Comparative Example 3 Sol. 18 Film 18 450 Resist film — —120 Undercoat film — — 90

Separately, a rate of O₂ gas dry etching was examined under thefollowing set of etching conditions (2). The results are shown in Table4.

(2) O₂ Gas Etching Test

-   -   Chamber pressure: 60.0 Pa    -   RF power: 600 W    -   Ar gas flow rate: 40 ml/min    -   O₂ gas flow rate: 60 ml/min    -   Gap: 9 mm    -   Treating time: 20 sec

TABLE 4 Metal oxide-containing O₂ gas etching rate film (nm/min) Example1 Film 1  2 Example 2 Film 2  2 Example 3 Film 3  2 Example 4 Film 4  2Example 5 Film 5  1 Example 6 Film 6  2 Example 7 Film 7  2 Example 8Film 8  1 Example 9 Film 9  3 Example 10 Film 10 3 Example 11 Film 11 4Example 12 Film 12 4 Example 13 Film 13 3 Example 14 Film 14 3 Example15 Film 15 2 Comparative Example 1 Film 16 3 Comparative Example 2 Film17 2 Comparative Example 3 Film 18 2 Resist film — 250 Undercoat film —210

It is seen that as compared with the undercoat film and the overcoatresist film, the metal oxide-containing intermediate films have a lowetching rate sufficient to use them as an etching mask in transferringthe pattern to the underlying layer.

Furthermore, a shelf stability test was performed. The metaloxide-containing film forming compositions (Sol. 1 to 18) prepared abovewere stored at 30° C. for 3 months, following which they were coated bythe above-mentioned technique. It was examined whether any change offilm formation occurred before and after the storage. The results areshown in Table 5.

TABLE 5 Metal oxide-containing film-forming composition State as coatedExample 1 Sol. 1  no thickness change, no pattern profile change Example2 Sol. 2  no thickness change, no pattern profile change Example 3 Sol.3  no thickness change, no pattern profile change Example 4 Sol. 4  nothickness change, no pattern profile change Example 5 Sol. 5  nothickness change, no pattern profile change Example 6 Sol. 6  nothickness change, no pattern profile change Example 7 Sol. 7  nothickness change, no pattern profile change Example 8 Sol. 8  nothickness change, no pattern profile change Example 9 Sol. 9  nothickness change, no pattern profile change Example 10 Sol. 10 nothickness change, no pattern profile change Example 11 Sol. 11 nothickness change, no pattern profile change Example 12 Sol. 12 nothickness change, no pattern profile change Example 13 Sol. 13 nothickness change, no pattern profile change Example 14 Sol. 14 nothickness change, no pattern profile change Example 15 Sol. 15 nothickness change, no pattern profile change Comparative Example 1 Sol.16 no thickness change, pattern stripped Comparative Example 2 Sol. 1715% thickness increase, pattern stripped Comparative Example 3 Sol. 185% thickness increase, pattern stripped

It is seen from Table 5 that all the compositions of Examples remainstable at 30° C. over 3 months, corresponding to shelf stability at roomtemperature over 6 months.

The composition of the invention and the metal oxide-containing filmthereof are improved in stability and lithographic characteristics. Theinventive composition enables pattern formation using the advancedhigh-NA exposure system and substrate processing by etching.

Japanese Patent Application No. 2007-303130 is incorporated herein byreference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A heat curable metal oxide-containing film-forming compositioncomprising (A) a metal oxide-containing compound obtained throughhydrolytic condensation between one or multiple hydrolyzable siliconcompounds having the general formula (1) and one or multiplehydrolyzable metal compounds having the general formula (2):R¹ _(m1)R² _(m2)R³ _(m3)Si(OR)_((4-m1-m2-m3))   (1) wherein R is analkyl of 1 to 6 carbon atoms, R¹, R² and R³ each are hydrogen or amonovalent organic group of 1 to 30 is carbon atoms, m1, m2 and m3 eachare 0 or 1, and m1+m2+m3 is an integer of 0 to 3,U(OR⁴)_(m4)(OR⁵)_(m5)   (2) wherein U is an element selected from GroupIII, IV and V elements in the Periodic Table, excluding silicon, R⁴ andR⁵ each are an organic group of 1 to 30 carbon atoms, m4 and m5 each arean integer inclusive of 0, and m4+m5 is equal to the valence of U, (B)at least one compound having the general formula (3) or (4):L_(a)H_(b)X   (3) wherein L is lithium, sodium, potassium, rubidium orcesium, X is a hydroxyl group or a mono or polyfunctional organic acidresidue of 1 to 30 carbon atoms, “a” is an integer of at least 1, “b” is0 or an integer of at least 1, and a+b is equal to the valence ofhydroxyl group or organic acid residue,M_(a)H_(b)A   (4) wherein M is sulfonium, iodonium or ammonium, A is Xor a non-nucleophilic counter ion, “a” and “b” are as defined above, anda+b is equal to the valence of hydroxyl group, organic acid residue ornon-nucleophilic counter ion, (C) a mono or polyfunctional organic acidof 1 to 30 carbon atoms, and (D) an organic solvent.
 2. The compositionof claim 1, further comprising (E) a silicon-containing compoundobtained through hydrolytic condensation of one or multiple hydrolyzablesilicon compounds having the general formula (5):R⁶ _(m6)R⁷ _(m7)R⁸ _(m8)Si(OR⁹)_((4-m6-m7-m8))   (5) wherein R⁹ is analkyl of 1 to 6 carbon atoms, R⁶, R⁷ and R⁸ each are hydrogen or amonovalent organic group of 1 to 30 carbon atoms, m6, m7 and m8 each are0 or 1, and m6+m7+m8 is an integer of 0 to
 3. 3. The composition ofclaim 1 wherein the metal oxide-containing compound (A) is obtainedthrough hydrolytic condensation between the compounds having the generalformulae (1) and (2) in the presence of an acid catalyst.
 4. Thecomposition of claim 3 wherein said acid catalyst comprises at least onecompound selected from mineral acids and sulfonic acid derivatives. 5.The composition of claim 3 wherein the metal oxide-containing compound(A) comprises a metal oxide-containing compound obtained bysubstantially removing the acid catalyst from a reaction mixtureresulting from hydrolytic condensation between the compounds havingformulae (1) and (2).
 6. The composition of claim 1 wherein U in formula(2) is selected from the group consisting of boron, aluminum, gallium,yttrium, germanium, titanium, zirconium, hafnium, bismuth, tin,phosphorus, vanadium, arsenic, antimony, niobium, and tantalum.
 7. Thecomposition of claim 1 wherein the compound of formula (1) is used in agreater molar amount than the compound of formula (2) during hydrolyticcondensation.
 8. The composition of claim 1 wherein M in formula (4) istertiary sulfonium, secondary iodonium, or quaternary ammonium.
 9. Thecomposition of claim 1 wherein M in formula (4) is photo-degradable. 10.The composition of claim 1, further comprising water.
 11. Thecomposition of claim 1, further comprising a photoacid generator. 12.The composition of claim 1, further comprising a mono or polyhydricalcohol substituted with a cyclic ether.
 13. A metal oxide-containingfilm for use in a multilayer resist process involving the steps offorming an organic film on a processable substrate, forming a metaloxide-containing film thereon, further forming a resist film thereonfrom a silicon-free chemically amplified resist composition, patterningthe resist film, patterning the metal oxide-containing film using theresist film pattern, patterning the underlying organic film with themetal oxide-containing film pattern made an etching mask, and etchingthe processable substrate with the patterned organic film made anetching mask, the metal oxide-containing film being formed from thecomposition of claim
 1. 14. The metal oxide-containing film of claim 13wherein the process further involves the step of disposing an organicantireflective coating between the resist film and the metaloxide-containing film.
 15. A substrate having formed thereon, insequence, an organic film, a metal oxide-containing film of thecomposition of claim 1, and a photoresist film.
 16. The substrate ofclaim 15 further having an organic antireflective coating between themetal oxide-containing film and the photoresist film.
 17. The substrateof claim 15 wherein said organic film is a film having an aromaticframework.
 18. A method for forming a pattern in a substrate, comprisingthe steps of: providing the substrate of claim 15, exposing a patterncircuit region of the photoresist film to radiation, developing thephotoresist film with a developer to form a resist pattern, dry etchingthe metal oxide-containing film with the resist pattern made an etchingmask, etching the organic film with the patterned metal oxide-containingfilm made an etching mask, and etching the substrate with the patternedorganic film made an etching mask, for forming a pattern in thesubstrate.
 19. A method for forming a pattern in a substrate, comprisingthe steps of: providing the substrate of claim 16, exposing a patterncircuit region of the photoresist film to radiation, developing thephotoresist film with a developer to form a resist pattern, dry etchingthe organic antireflective coating and the metal oxide-containing filmwith the resist pattern made an etching mask, etching the organic filmwith the patterned metal oxide-containing film made an etching mask, andetching the substrate with the patterned organic film made an etchingmask, for forming a pattern in the substrate.
 20. The patterning methodof claim 18 wherein said organic film is a film having an aromaticframework.
 21. The patterning method of claim 18 wherein the exposingstep is carried out by photolithography using radiation having awavelength equal to or less than 300 nm.